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[109.15.145.210]) by smtp.googlemail.com with ESMTPSA id j8-20020a05600c1c0800b003c6b7f5567csm10325280wms.0.2022.10.21.06.31.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Oct 2022 06:31:37 -0700 (PDT) From: Amjad Ouled-Ameur Date: Fri, 21 Oct 2022 15:31:26 +0200 Subject: [PATCH v4 2/4] spi: meson-spicc: Use pinctrl to drive CLK line when idle MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20221004-up-aml-fix-spi-v4-2-0342d8e10c49@baylibre.com> References: <20221004-up-aml-fix-spi-v4-0-0342d8e10c49@baylibre.com> In-Reply-To: <20221004-up-aml-fix-spi-v4-0-0342d8e10c49@baylibre.com> To: Kevin Hilman , Jerome Brunet , Rob Herring , Martin Blumenstingl , Neil Armstrong , Krzysztof Kozlowski , Mark Brown Cc: linux-amlogic@lists.infradead.org, Neil Armstrong , Amjad Ouled-Ameur , Da Xue , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org X-Mailer: b4 0.10.1 X-Developer-Signature: v=1; a=ed25519-sha256; t=1666359095; l=3653; i=aouledameur@baylibre.com; s=20220920; h=from:subject:message-id; bh=IGy2/xUGkATMfFoSdC/ARGihk37oQRhTPB+1EALz76c=; b=lVbVZDfVeI3MW+9qrIowJAsQyvBv8U545pKIoqjO0+YgyhER33t3/Zp4VbbqGrx+MhjLkqs7IHRU trZgoLn6ClcWt9mGnWI8aZXWutDyPed/A0gmPad7hkEfKs89DPgl X-Developer-Key: i=aouledameur@baylibre.com; a=ed25519; pk=HgYWawSL4qLGPx+RzJ+Cuu+V8Pi/KQnDDm1wjWPMOFE= Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Between SPI transactions, all SPI pins are in HiZ state. When using the SS signal from the SPICC controller it's not an issue because when the transaction resumes all pins come back to the right state at the same time as SS. The problem is when we use CS as a GPIO. In fact, between the GPIO CS state change and SPI pins state change from idle, you can have a missing or spurious clock transition. Set a bias on the clock depending on the clock polarity requested before CS goes active, by passing a special "idle-low" and "idle-high" pinctrl state and setting the right state at a start of a message Reported-by: Da Xue Signed-off-by: Neil Armstrong Signed-off-by: Amjad Ouled-Ameur Reviewed-by: Martin Blumenstingl --- drivers/spi/spi-meson-spicc.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c index bad201510a99..ffea38e2339c 100644 --- a/drivers/spi/spi-meson-spicc.c +++ b/drivers/spi/spi-meson-spicc.c @@ -21,6 +21,7 @@ #include #include #include +#include =20 /* * The Meson SPICC controller could support DMA based transfers, but is not @@ -167,6 +168,9 @@ struct meson_spicc_device { unsigned long tx_remain; unsigned long rx_remain; unsigned long xfer_remain; + struct pinctrl *pinctrl; + struct pinctrl_state *pins_idle_high; + struct pinctrl_state *pins_idle_low; }; =20 #define pow2_clk_to_spicc(_div) container_of(_div, struct meson_spicc_devi= ce, pow2_div) @@ -175,8 +179,22 @@ static void meson_spicc_oen_enable(struct meson_spicc_= device *spicc) { u32 conf; =20 - if (!spicc->data->has_oen) + if (!spicc->data->has_oen) { + /* Try to get pinctrl states for idle high/low */ + spicc->pins_idle_high =3D pinctrl_lookup_state(spicc->pinctrl, + "idle-high"); + if (IS_ERR(spicc->pins_idle_high)) { + dev_warn(&spicc->pdev->dev, "can't get idle-high pinctrl\n"); + spicc->pins_idle_high =3D NULL; + } + spicc->pins_idle_low =3D pinctrl_lookup_state(spicc->pinctrl, + "idle-low"); + if (IS_ERR(spicc->pins_idle_low)) { + dev_warn(&spicc->pdev->dev, "can't get idle-low pinctrl\n"); + spicc->pins_idle_low =3D NULL; + } return; + } =20 conf =3D readl_relaxed(spicc->base + SPICC_ENH_CTL0) | SPICC_ENH_MOSI_OEN | SPICC_ENH_CLK_OEN | SPICC_ENH_CS_OEN; @@ -441,6 +459,16 @@ static int meson_spicc_prepare_message(struct spi_mast= er *master, else conf &=3D ~SPICC_POL; =20 + if (!spicc->data->has_oen) { + if (spi->mode & SPI_CPOL) { + if (spicc->pins_idle_high) + pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_high); + } else { + if (spicc->pins_idle_low) + pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_low); + } + } + if (spi->mode & SPI_CPHA) conf |=3D SPICC_PHA; else @@ -487,6 +515,9 @@ static int meson_spicc_unprepare_transfer(struct spi_ma= ster *master) /* Set default configuration, keeping datarate field */ writel_relaxed(conf, spicc->base + SPICC_CONREG); =20 + if (!spicc->data->has_oen) + pinctrl_select_default_state(&spicc->pdev->dev); + return 0; } =20 @@ -798,6 +829,12 @@ static int meson_spicc_probe(struct platform_device *p= dev) goto out_core_clk; } =20 + spicc->pinctrl =3D devm_pinctrl_get(&pdev->dev); + if (IS_ERR(spicc->pinctrl)) { + ret =3D PTR_ERR(spicc->pinctrl); + goto out_clk; + } + device_reset_optional(&pdev->dev); =20 master->num_chipselect =3D 4; --=20 b4 0.10.1