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[61.228.48.72]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2cf3477eecdsm28084155ad.78.2026.07.18.07.52.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Jul 2026 07:52:14 -0700 (PDT) From: Shih-Yuan Lee To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Shih-Yuan Lee Subject: [PATCH v12 1/3] spi: pxa2xx: disable DMA for Apple MacBook8,1 Date: Sat, 18 Jul 2026 22:52:07 +0800 Message-Id: <20260718145209.6678-2-fourdollars@debian.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260718145209.6678-1-fourdollars@debian.org> References: <20260718145209.6678-1-fourdollars@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" On MacBook8,1 (early 2015 12" MacBook), the LPSS SPI controller at 00:15.4 suffers from hardware DMA handshake failures and interrupt routing bugs, causing keyboard/touchpad transactions to fail when DMA is enabled. Move the forced PIO mode DMI quirk to spi-pxa2xx-pci.c (the LPSS host controller PCI glue driver) to avoid layering violations in client drivers (such as applespi). Add an explicit DMI match table for MacBook8,1 and a module parameter spi_pxa2xx_force_pio to allow forcing PIO mode on demand. Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D108331 Signed-off-by: Shih-Yuan Lee --- drivers/spi/spi-pxa2xx-pci.c | 35 +++++++++++++++++++++++++++++++++-- 1 file changed, 33 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi-pxa2xx-pci.c b/drivers/spi/spi-pxa2xx-pci.c index cae77ac18520..31bdaa096d9e 100644 --- a/drivers/spi/spi-pxa2xx-pci.c +++ b/drivers/spi/spi-pxa2xx-pci.c @@ -18,9 +18,14 @@ =20 #include #include +#include =20 #include "spi-pxa2xx.h" =20 +static bool spi_pxa2xx_force_pio; +module_param_named(force_pio, spi_pxa2xx_force_pio, bool, 0444); +MODULE_PARM_DESC(force_pio, "Force PIO mode (disables DMA) for SPI transfe= rs. ([0] =3D disabled, 1 =3D enabled)"); + #define PCI_DEVICE_ID_INTEL_QUARK_X1000 0x0935 #define PCI_DEVICE_ID_INTEL_BYT 0x0f0e #define PCI_DEVICE_ID_INTEL_MRFLD 0x1194 @@ -93,6 +98,32 @@ static void lpss_dma_put_device(void *dma_dev) pci_dev_put(dma_dev); } =20 +static const struct dmi_system_id pxa2xx_spi_pci_dmi_table[] =3D { + { + .ident =3D "Apple MacBook8,1", + .matches =3D { + DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."), + DMI_MATCH(DMI_PRODUCT_NAME, "MacBook8,1"), + }, + }, + { } +}; + +static bool pxa2xx_spi_pci_can_dma(struct pci_dev *dev) +{ + if (spi_pxa2xx_force_pio) { + pci_info(dev, "Forcing PIO mode (disabling DMA)\n"); + return false; + } + + if (dmi_check_system(pxa2xx_spi_pci_dmi_table)) { + pci_info(dev, "MacBook8,1 detected: disabling DMA to force PIO mode\n"); + return false; + } + + return true; +} + static int lpss_spi_setup(struct pci_dev *dev, struct pxa2xx_spi_controlle= r *c) { struct ssp_device *ssp =3D &c->ssp; @@ -166,7 +197,7 @@ static int lpss_spi_setup(struct pci_dev *dev, struct p= xa2xx_spi_controller *c) =20 c->dma_filter =3D lpss_dma_filter; c->dma_burst_size =3D 1; - c->enable_dma =3D 1; + c->enable_dma =3D pxa2xx_spi_pci_can_dma(dev); return 0; } =20 @@ -238,7 +269,7 @@ static int mrfld_spi_setup(struct pci_dev *dev, struct = pxa2xx_spi_controller *c) =20 c->dma_filter =3D lpss_dma_filter; c->dma_burst_size =3D 8; - c->enable_dma =3D 1; + c->enable_dma =3D pxa2xx_spi_pci_can_dma(dev); return 0; } =20 --=20 2.39.5 From nobody Sat Jul 25 04:29:55 2026 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E47E0846F for ; Sat, 18 Jul 2026 14:52:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.176 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784386345; cv=none; b=jmwbUMJOqtUuOsGs5SnS6vIWk0CqRNUFYc8JalrtzoOMr+tS+hCcpo0MsB84CjWnsqiHMVV4R75WYkrwK4u2yM9gW0OYT8zwAoFLk0B9pO5987La27DL5gEa9cXT21hnmSuJIJdaPdhxr12Wcsj1PKjcfAFKU7jGt89K1j1LKek= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784386345; c=relaxed/simple; bh=VJfvJu4oyqkg1cLNVPS7cqo9EhGVu2i6n2tKtQCEyMQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=qDAH5HV0kfIWAGnO7GRXEt9EbtVARflrBmfRKiwwsWcToVCDJnESMstqwkDf+7kAK0v1h/Bs0v8TmdyHhT1ualep1iJcY0QSUen0JqkWUH572HFibOcUcIknOCiDkM/AQQv5QzTP2rstVNOZyOBc+SS8Pc2E9vKzH0ZveK6shik= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.214.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pl1-f176.google.com with SMTP id d9443c01a7336-2ce98cb8165so27272335ad.1 for ; Sat, 18 Jul 2026 07:52:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784386337; x=1784991137; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=SZgM+T32rwA8zwNpdGf6ULHHrTn7ipcjxObpbX1+QDI=; b=iaGJO9H+gyR6rP03sUHMG3boScbO4JeupXWQICDGBPqA5KucgA1dIZEM/7gfNLH7or 9SO1LxmgpYJKg6ycGGKsUTm2GZIm/vJBL0EUC/wA1uhAIdENz/d0rI2Poqdp7vECdTom Xlu1s/1dGJEA4Cg3HD+Izt3nmeOGAew0uUEKbAFgZQCL/0MxpueK6VLrH/mh4wIHd0qm 3De5rNn7CB4Mcy+7ahpdr5ipJbTSKMwvTmBrW+qTy4mmnPJgLF6bR7yI4uFrvXYQ5t/x q+O+Oz/U3XvXXN84rDPR/na0u3VEewjTjnts38DgNMaetl65PpSO6ylW8KnKWj2tOkGX e3nw== X-Forwarded-Encrypted: i=1; AHgh+RpMKeLBxLH0RBKe5mwDitD5FGizokvnWTD/Keohg9b1iSpaaDiwO2495WZr/35oh28/ETLylpdlzNiDa/0=@vger.kernel.org X-Gm-Message-State: AOJu0YzOuNoL5b7EevOqpsC4MGBTSRqAFAxi3aji+WEp9PD6rkVR0O4c qY91gH8avKavx+owmhhqbeGl1/UllA52bLBRPbZGvpal3PSRZNurDfn/SNlewDVjvg== X-Gm-Gg: AfdE7cmtHodzBbOMHqniPfJ3LrMjeh33ItLV/BxKkxY7o7gzGLf1geqT8VPcKvcNdH7 9EI6qwAFJQ/eD3Xw38T5YSIXOt5jgWTrFYmVEMy6hNvarlKcQFCkeGmGGptdMzeV8vNYEW+7lFm 6J5pWaU+vQz1y3k6q10MTT0mAJmJ9gxzNLkEF8n51k7mlwl1m73k2w/1v+LKWxDdFa/zl0VPjaD ffNJ7GGHn26CtZYDc/W4ROa+JHcIZu9JgYnPxnoVtTEK0b6EY/U8RElmJUJAaH7TbBuCkduCwsn GpfmfoPHlJQeUVbD86iAGXhrzDLIjXdVaVodxlbq5z0Tl9jQ3MfQLkd8ztch5KsUT+0vsJker2J uJzaJrE2dZN56saW71wgqLhIGHwZU5dQdI31C7FfAVH3CQzjTZLe+Gtmghnxva0NZgQWUDglEwP SwxpUDL/92Tmbfslp9h8djkOHYhYtNJM6sc+Jn4vgVRBMRnUztC2/4lwS4PPQ+UnFBPfzHuzSFC r9vK3HMYnV/dM4= X-Received: by 2002:a17:902:d501:b0:2c9:d8c5:d55d with SMTP id d9443c01a7336-2cf349bc5e1mr72658165ad.16.1784386336995; Sat, 18 Jul 2026 07:52:16 -0700 (PDT) Received: from penguin.tail0a1999.ts.net (61-228-48-72.dynamic-ip.hinet.net. [61.228.48.72]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2cf3477eecdsm28084155ad.78.2026.07.18.07.52.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Jul 2026 07:52:16 -0700 (PDT) From: Shih-Yuan Lee To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Shih-Yuan Lee Subject: [PATCH v12 2/3] spi: pxa2xx: fix runtime PM and interrupt handling in PIO mode Date: Sat, 18 Jul 2026 22:52:08 +0800 Message-Id: <20260718145209.6678-3-fourdollars@debian.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260718145209.6678-1-fourdollars@debian.org> References: <20260718145209.6678-1-fourdollars@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When operating in PIO mode on Intel LPSS SPI controllers, runtime PM autosuspend clock-gates the hardware block, causing PCIe Completion Timeouts on subsequent MMIO accesses. To fix this: - Scope PIO mode autosuspend lockout (pm_runtime_get_noresume() / put_sync()) strictly to LPSS controllers via is_lpss_ssp(), preserving autosuspend for non-LPSS SoCs. - Acquire pm_runtime_get_noresume() exactly once in pxa2xx_spi_probe() after spi_register_controller() succeeds, and release it via pm_runtime_put_sync() in pxa2xx_spi_remove(). Using pm_runtime_put_sync() ensures the runtime PM state machine transitions to RPM_SUSPENDED upon driver unbind, preventing active child count leaks on the parent LPSS power domain. - Track clock state using drv_data->clk_enabled in helper functions pxa2xx_spi_clk_enable/disable() to prevent clock count underflows on error paths. - Protect ssp_int() using drv_data->clk_enabled, drv_data->suspended, and checking pm_runtime_get_if_active() =3D=3D 0 to return IRQ_NONE immediate= ly, avoiding unclocked MMIO reads and level-triggered shared IRQ storms. - Register IRQ in probe only after enabling the clock and clearing suspended. - Overhaul pxa2xx_spi_remove() teardown sequence: disable SSP hardware IRQ, set suspended flag, synchronize IRQ, free IRQ, and disable clocks. - Guard MMIO access in pxa2xx_spi_runtime_suspend() with drv_data->clk_enabled check. Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D108331 Signed-off-by: Shih-Yuan Lee --- drivers/spi/spi-pxa2xx.c | 152 ++++++++++++++++++++++++++++++--------- drivers/spi/spi-pxa2xx.h | 3 + 2 files changed, 120 insertions(+), 35 deletions(-) diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c index 6291d7c2e06f..a9da0c3a358a 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -72,7 +72,12 @@ struct chip_data { #define LPSS_CAPS_CS_EN_SHIFT 9 #define LPSS_CAPS_CS_EN_MASK (0xf << LPSS_CAPS_CS_EN_SHIFT) =20 -#define LPSS_PRIV_CLOCK_GATE 0x38 +/* Offsets from drv_data->lpss_base */ +#define LPSS_PRIV_RESETS 0x04 +#define LPSS_PRIV_RESETS_IDMA BIT(2) +#define LPSS_PRIV_RESETS_FUNC 0x3 + +#define LPSS_PRIV_CLOCK_GATE 0x38 #define LPSS_PRIV_CLOCK_GATE_CLK_CTL_MASK 0x3 #define LPSS_PRIV_CLOCK_GATE_CLK_CTL_FORCE_ON 0x3 #define LPSS_PRIV_CLOCK_GATE_CLK_CTL_FORCE_OFF 0x0 @@ -713,20 +718,42 @@ static void handle_bad_msg(struct driver_data *drv_da= ta) dev_err(drv_data->ssp->dev, "bad message state in interrupt handler\n"); } =20 +static int pxa2xx_spi_clk_enable(struct driver_data *drv_data) +{ + int status; + + if (drv_data->clk_enabled) + return 0; + + status =3D clk_prepare_enable(drv_data->ssp->clk); + if (status =3D=3D 0) + drv_data->clk_enabled =3D true; + + return status; +} + +static void pxa2xx_spi_clk_disable(struct driver_data *drv_data) +{ + if (drv_data->clk_enabled) { + clk_disable_unprepare(drv_data->ssp->clk); + drv_data->clk_enabled =3D false; + } +} + static irqreturn_t ssp_int(int irq, void *dev_id) { struct driver_data *drv_data =3D dev_id; u32 sccr1_reg; u32 mask =3D drv_data->mask_sr; u32 status; + int active; + irqreturn_t ret =3D IRQ_NONE; =20 - /* - * The IRQ might be shared with other peripherals so we must first - * check that are we RPM suspended or not. If we are we assume that - * the IRQ was not for us (we shouldn't be RPM suspended when the - * interrupt is enabled). - */ - if (pm_runtime_suspended(drv_data->ssp->dev)) + if (drv_data->suspended || !drv_data->clk_enabled) + return IRQ_NONE; + + active =3D pm_runtime_get_if_active(drv_data->ssp->dev); + if (active =3D=3D 0) return IRQ_NONE; =20 /* @@ -737,7 +764,7 @@ static irqreturn_t ssp_int(int irq, void *dev_id) */ status =3D pxa2xx_spi_read(drv_data, SSSR); if (status =3D=3D ~0) - return IRQ_NONE; + goto out_put; =20 sccr1_reg =3D pxa2xx_spi_read(drv_data, SSCR1); =20 @@ -750,7 +777,7 @@ static irqreturn_t ssp_int(int irq, void *dev_id) mask &=3D ~SSSR_TINT; =20 if (!(status & mask)) - return IRQ_NONE; + goto out_put; =20 pxa2xx_spi_write(drv_data, SSCR1, sccr1_reg & ~drv_data->int_cr1); pxa2xx_spi_write(drv_data, SSCR1, sccr1_reg); @@ -758,10 +785,19 @@ static irqreturn_t ssp_int(int irq, void *dev_id) if (!drv_data->controller->cur_msg) { handle_bad_msg(drv_data); /* Never fail */ - return IRQ_HANDLED; + ret =3D IRQ_HANDLED; + goto out_put; + } + + ret =3D drv_data->transfer_handler(drv_data); + +out_put: + if (active > 0) { + pm_runtime_mark_last_busy(drv_data->ssp->dev); + pm_runtime_put_autosuspend(drv_data->ssp->dev); } =20 - return drv_data->transfer_handler(drv_data); + return ret; } =20 /* @@ -1288,6 +1324,7 @@ int pxa2xx_spi_probe(struct device *dev, struct ssp_d= evice *ssp, drv_data->controller =3D controller; drv_data->controller_info =3D platform_info; drv_data->ssp =3D ssp; + drv_data->suspended =3D true; /* Start suspended until clock is enabled */ =20 /* The spi->mode bits understood by this driver: */ controller->mode_bits =3D SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LOOP; @@ -1330,10 +1367,6 @@ int pxa2xx_spi_probe(struct device *dev, struct ssp_= device *ssp, | SSSR_ROR | SSSR_TUR; } =20 - status =3D request_irq(ssp->irq, ssp_int, IRQF_SHARED, dev_name(dev), - drv_data); - if (status < 0) - return dev_err_probe(dev, status, "cannot get IRQ %d\n", ssp->irq); =20 /* Setup DMA if requested */ if (platform_info->enable_dma) { @@ -1352,9 +1385,18 @@ int pxa2xx_spi_probe(struct device *dev, struct ssp_= device *ssp, } =20 /* Enable SOC clock */ - status =3D clk_prepare_enable(ssp->clk); + status =3D pxa2xx_spi_clk_enable(drv_data); if (status) - goto out_error_dma_irq_alloc; + goto out_error_dma_alloc; + + drv_data->suspended =3D false; + + status =3D request_irq(ssp->irq, ssp_int, IRQF_SHARED, dev_name(dev), + drv_data); + if (status < 0) { + status =3D dev_err_probe(dev, status, "cannot get IRQ %d\n", ssp->irq); + goto out_error_clock_enabled; + } =20 controller->max_speed_hz =3D clk_get_rate(ssp->clk); /* @@ -1434,7 +1476,7 @@ int pxa2xx_spi_probe(struct device *dev, struct ssp_d= evice *ssp, "ready", GPIOD_OUT_LOW); if (IS_ERR(drv_data->gpiod_ready)) { status =3D PTR_ERR(drv_data->gpiod_ready); - goto out_error_clock_enabled; + goto out_error_irq_alloc; } } =20 @@ -1443,17 +1485,22 @@ int pxa2xx_spi_probe(struct device *dev, struct ssp= _device *ssp, status =3D spi_register_controller(controller); if (status) { dev_err_probe(dev, status, "problem registering SPI controller\n"); - goto out_error_clock_enabled; + goto out_error_irq_alloc; } =20 + if (is_lpss_ssp(drv_data) && !platform_info->enable_dma) + pm_runtime_get_noresume(dev); + return status; =20 +out_error_irq_alloc: + free_irq(ssp->irq, drv_data); + out_error_clock_enabled: - clk_disable_unprepare(ssp->clk); + pxa2xx_spi_clk_disable(drv_data); =20 -out_error_dma_irq_alloc: +out_error_dma_alloc: pxa2xx_spi_dma_release(drv_data); - free_irq(ssp->irq, drv_data); =20 return status; } @@ -1466,16 +1513,26 @@ void pxa2xx_spi_remove(struct device *dev) =20 spi_unregister_controller(drv_data->controller); =20 - /* Disable the SSP at the peripheral and SOC level */ + /* Disable SSP interrupt generation on hardware level while clock is acti= ve */ pxa_ssp_disable(ssp); - clk_disable_unprepare(ssp->clk); =20 - /* Release DMA */ - if (drv_data->controller_info->enable_dma) - pxa2xx_spi_dma_release(drv_data); + /* Mark as suspended to prevent further IRQ handling */ + drv_data->suspended =3D true; + + /* Wait for any pending interrupt handlers to complete */ + synchronize_irq(ssp->irq); =20 /* Release IRQ */ free_irq(ssp->irq, drv_data); + + /* Safe to disable the SSP clock now */ + pxa2xx_spi_clk_disable(drv_data); + + /* Release DMA */ + if (drv_data->controller_info->enable_dma) + pxa2xx_spi_dma_release(drv_data); + else if (is_lpss_ssp(drv_data)) + pm_runtime_put_sync(dev); } EXPORT_SYMBOL_NS_GPL(pxa2xx_spi_remove, "SPI_PXA2xx"); =20 @@ -1490,10 +1547,10 @@ static int pxa2xx_spi_suspend(struct device *dev) return status; =20 pxa_ssp_disable(ssp); + drv_data->suspended =3D true; + synchronize_irq(ssp->irq); =20 - if (!pm_runtime_suspended(dev)) - clk_disable_unprepare(ssp->clk); - + pxa2xx_spi_clk_disable(drv_data); return 0; } =20 @@ -1505,28 +1562,53 @@ static int pxa2xx_spi_resume(struct device *dev) =20 /* Enable the SSP clock */ if (!pm_runtime_suspended(dev)) { - status =3D clk_prepare_enable(ssp->clk); + status =3D pxa2xx_spi_clk_enable(drv_data); if (status) return status; } =20 + if (is_lpss_ssp(drv_data)) + lpss_ssp_setup(drv_data); + + drv_data->suspended =3D false; + /* Start the queue running */ - return spi_controller_resume(drv_data->controller); + status =3D spi_controller_resume(drv_data->controller); + if (status) { + drv_data->suspended =3D true; + synchronize_irq(ssp->irq); + pxa2xx_spi_clk_disable(drv_data); + return status; + } + + return 0; } =20 static int pxa2xx_spi_runtime_suspend(struct device *dev) { struct driver_data *drv_data =3D dev_get_drvdata(dev); =20 - clk_disable_unprepare(drv_data->ssp->clk); + if (!drv_data->clk_enabled) + return 0; + + pxa_ssp_disable(drv_data->ssp); + drv_data->suspended =3D true; + synchronize_irq(drv_data->ssp->irq); + pxa2xx_spi_clk_disable(drv_data); return 0; } =20 static int pxa2xx_spi_runtime_resume(struct device *dev) { struct driver_data *drv_data =3D dev_get_drvdata(dev); + int status; =20 - return clk_prepare_enable(drv_data->ssp->clk); + status =3D pxa2xx_spi_clk_enable(drv_data); + if (status) + return status; + + drv_data->suspended =3D false; + return 0; } =20 EXPORT_NS_GPL_DEV_PM_OPS(pxa2xx_spi_pm_ops, SPI_PXA2xx) =3D { diff --git a/drivers/spi/spi-pxa2xx.h b/drivers/spi/spi-pxa2xx.h index 447be0369384..44f37bf9c519 100644 --- a/drivers/spi/spi-pxa2xx.h +++ b/drivers/spi/spi-pxa2xx.h @@ -72,6 +72,9 @@ struct driver_data { =20 void __iomem *lpss_base; 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[61.228.48.72]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2cf3477eecdsm28084155ad.78.2026.07.18.07.52.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Jul 2026 07:52:18 -0700 (PDT) From: Shih-Yuan Lee To: Mark Brown Cc: linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, Shih-Yuan Lee Subject: [PATCH v12 3/3] spi: pxa2xx: restore LPSS private register state on S3 resume Date: Sat, 18 Jul 2026 22:52:09 +0800 Message-Id: <20260718145209.6678-4-fourdollars@debian.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260718145209.6678-1-fourdollars@debian.org> References: <20260718145209.6678-1-fourdollars@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Intel LPSS SPI controllers lose all private register state across S3 suspend because the LPSS power domain is fully removed. On resume the driver only re-enables the SSP clock, leaving the LPSS private registers in their power-on-reset state, which causes two problems: 1. LPSS_PRIV_RESETS (offset 0x04 within the LPSS private space) stays zero, keeping the functional block in reset. Any MMIO access while the block is held in reset causes a PCIe Completion Timeout and a watchdog-triggered system reset. LPSS_PRIV_RESETS_FUNC and LPSS_PRIV_RESETS_IDMA must be de-asserted before any other register access on resume. 2. The LPSS software chip-select control register must not be blindly restored from its suspend-time snapshot: if CS was asserted at the moment of suspend, restoring that state corrupts the first post-resume SPI transaction. Instead, call lpss_ssp_setup() which unconditionally writes SW_MODE | CS_HIGH (idle/deasserted), matching the state established at probe time. To resolve these issues safely: - Wrap S3 suspend/resume with pm_runtime_resume_and_get() and pm_runtime_put_autosuspend() to guarantee active clocks during MMIO access and preserve PM reference counting. - Restrict LPSS private register save/restore to LPT, BYT, and BSW platforms via pxa2xx_spi_need_lpss_restore() (newer platforms are handled by intel-lpss.c). - Save only the first 6 LPSS private registers (offsets 0x00..0x14) in drv_data during suspend, avoiding reserved offsets beyond 0x14. - On resume, de-assert resets first, restore saved registers, call lpss_ssp_setup(), and clear drv_data->suspended to prevent unclocked IRQ access. - Add error recovery paths for spi_controller_suspend/resume failures. Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D108331 Signed-off-by: Shih-Yuan Lee --- drivers/spi/spi-pxa2xx.c | 94 +++++++++++++++++++++++++++++++++++++--- drivers/spi/spi-pxa2xx.h | 1 + 2 files changed, 89 insertions(+), 6 deletions(-) diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c index a9da0c3a358a..507deef3e246 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -194,6 +194,18 @@ static bool is_lpss_ssp(const struct driver_data *drv_= data) } } =20 +static bool pxa2xx_spi_need_lpss_restore(const struct driver_data *drv_dat= a) +{ + switch (drv_data->ssp_type) { + case LPSS_LPT_SSP: + case LPSS_BYT_SSP: + case LPSS_BSW_SSP: + return true; + default: + return false; + } +} + static bool is_quark_x1000_ssp(const struct driver_data *drv_data) { return drv_data->ssp_type =3D=3D QUARK_X1000_SSP; @@ -1542,16 +1554,46 @@ static int pxa2xx_spi_suspend(struct device *dev) struct ssp_device *ssp =3D drv_data->ssp; int status; =20 - status =3D spi_controller_suspend(drv_data->controller); - if (status) + status =3D pm_runtime_resume_and_get(dev); + if (status < 0) return status; =20 + status =3D spi_controller_suspend(drv_data->controller); + if (status) { + spi_controller_resume(drv_data->controller); + goto out_put; + } + + /* Disable SSP interrupt generation on hardware level while clock is acti= ve */ pxa_ssp_disable(ssp); + + /* Mark as suspended and synchronize IRQ before disabling clock */ drv_data->suspended =3D true; synchronize_irq(ssp->irq); =20 + if (pxa2xx_spi_need_lpss_restore(drv_data)) { + unsigned int i; + + /* + * Save the first 6 LPSS private registers (offsets 0x00 to 0x14) + * while the clock is still enabled. They are lost when the LPSS + * power domain is removed across S3 and must be restored on resume. + * Use drv_data->lpss_base so the correct per-platform offset + * is applied regardless of LPSS IP revision. + * Registers beyond 0x14 (except CS control at 0x18) are reserved + * or unimplemented on LPT, and accessing them triggers a PCIe + * Completion Timeout causing a system halt. + */ + for (i =3D 0; i < 6; i++) + drv_data->lpss_priv_ctx[i] =3D readl(drv_data->lpss_base + i * 4); + } + pxa2xx_spi_clk_disable(drv_data); return 0; + +out_put: + pm_runtime_put_noidle(dev); + return status; } =20 static int pxa2xx_spi_resume(struct device *dev) @@ -1564,12 +1606,47 @@ static int pxa2xx_spi_resume(struct device *dev) if (!pm_runtime_suspended(dev)) { status =3D pxa2xx_spi_clk_enable(drv_data); if (status) - return status; + goto out_put; } =20 - if (is_lpss_ssp(drv_data)) + if (pxa2xx_spi_need_lpss_restore(drv_data)) { + unsigned int i; + + /* + * The LPSS power domain is removed across S3, taking + * all private registers with it. De-assert the + * functional block and IDMA resets first; any MMIO + * access while the block is held in reset causes a + * PCIe Completion Timeout and a watchdog-triggered + * system reset. + */ + writel(LPSS_PRIV_RESETS_FUNC | LPSS_PRIV_RESETS_IDMA, + drv_data->lpss_base + LPSS_PRIV_RESETS); + + /* Restore the other 5 saved private registers */ + for (i =3D 0; i < 6; i++) { + if (i =3D=3D LPSS_PRIV_RESETS / 4) + continue; + writel(drv_data->lpss_priv_ctx[i], + drv_data->lpss_base + i * 4); + } + } + + if (is_lpss_ssp(drv_data)) { + /* + * Re-initialise the SW chip-select control register so + * CS starts deasserted (SW_MODE | CS_HIGH), regardless + * of the state it was in at suspend time. A stale + * asserted CS on the first post-resume transaction + * corrupts the write-status response from the device. + */ lpss_ssp_setup(drv_data); + } =20 + /* + * Now that resets are de-asserted and registers are restored, + * it is safe to handle interrupts. + */ drv_data->suspended =3D false; =20 /* Start the queue running */ @@ -1578,10 +1655,15 @@ static int pxa2xx_spi_resume(struct device *dev) drv_data->suspended =3D true; synchronize_irq(ssp->irq); pxa2xx_spi_clk_disable(drv_data); - return status; + goto out_put; } =20 - return 0; +out_put: + /* Let runtime PM autosuspend again if needed */ + pm_runtime_mark_last_busy(dev); + pm_runtime_put_autosuspend(dev); + + return status; } =20 static int pxa2xx_spi_runtime_suspend(struct device *dev) diff --git a/drivers/spi/spi-pxa2xx.h b/drivers/spi/spi-pxa2xx.h index 44f37bf9c519..48169494f74e 100644 --- a/drivers/spi/spi-pxa2xx.h +++ b/drivers/spi/spi-pxa2xx.h @@ -71,6 +71,7 @@ struct driver_data { irqreturn_t (*transfer_handler)(struct driver_data *drv_data); =20 void __iomem *lpss_base; + u32 lpss_priv_ctx[6]; =20 bool suspended; bool clk_enabled; --=20 2.39.5