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Mon, 28 Jul 2025 22:44:46 -0700 (PDT) From: Brigham Campbell To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, linus.walleij@linaro.org, neil.armstrong@linaro.org, jessica.zhang@oss.qualcomm.com, sam@ravnborg.org Cc: dianders@chromium.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Brigham Campbell Subject: [PATCH v2 1/3] drm/panel: novatek-nt35560: Fix invalid return value Date: Mon, 28 Jul 2025 23:44:33 -0600 Message-ID: <20250729054435.1209156-2-me@brighamcampbell.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250729054435.1209156-1-me@brighamcampbell.com> References: <20250729054435.1209156-1-me@brighamcampbell.com> 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" Fix bug in nt35560_set_brightness() which causes the function to erroneously report an error. mipi_dsi_dcs_write() returns either a negative value when an error occurred or a positive number of bytes written when no error occurred. The buggy code reports an error under either condition. Fixes: 7835ed6a9e86 ("drm/panel-sony-acx424akp: Modernize backlight handlin= g") Signed-off-by: Brigham Campbell Reviewed-by: Douglas Anderson Reviewed-by: Neil Armstrong --- drivers/gpu/drm/panel/panel-novatek-nt35560.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35560.c b/drivers/gpu/dr= m/panel/panel-novatek-nt35560.c index 98f0782c8411..17898a29efe8 100644 --- a/drivers/gpu/drm/panel/panel-novatek-nt35560.c +++ b/drivers/gpu/drm/panel/panel-novatek-nt35560.c @@ -161,7 +161,7 @@ static int nt35560_set_brightness(struct backlight_devi= ce *bl) par =3D 0x00; ret =3D mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY, &par, 1); - if (ret) { + if (ret < 0) { dev_err(nt->dev, "failed to disable display backlight (%d)\n", ret); return ret; } --=20 2.50.1 From nobody Sun Oct 5 21:59:56 2025 Received: from mail-pf1-f169.google.com (mail-pf1-f169.google.com [209.85.210.169]) (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 8186F242D88 for ; 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charset="utf-8" Create mipi_dsi_dcs_read_multi(), which accepts a mipi_dsi_multi_context struct for improved error handling and cleaner panel driver code. Create mipi_dsi_dcs_write_var_seq_multi() and mipi_dsi_generic_write_var_seq_multi() macros which allow MIPI panel drivers to write non-static data to display controllers. Signed-off-by: Brigham Campbell Reviewed-by: Douglas Anderson --- I looked into using __builtin_constant_p() to extend mipi_dsi_{generic,dcs}_write_seq_multi() to accept both static and non-static sequences of bytes and store them accordingly, it looked promising at first, but I found no such solution ultimately. At the very least, if we find a solution at some point, my hope is that cocinelle could be used to replace each of the new var_seq_multi() usages among drivers with an improved seq_multi(). drivers/gpu/drm/drm_mipi_dsi.c | 37 ++++++++++++++++++++++++++++++++++ include/drm/drm_mipi_dsi.h | 35 ++++++++++++++++++++++++++++++++ 2 files changed, 72 insertions(+) diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c index a00d76443128..0f2c3be98212 100644 --- a/drivers/gpu/drm/drm_mipi_dsi.c +++ b/drivers/gpu/drm/drm_mipi_dsi.c @@ -1075,6 +1075,43 @@ ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *ds= i, u8 cmd, void *data, } EXPORT_SYMBOL(mipi_dsi_dcs_read); =20 +/** + * mipi_dsi_dcs_read_multi() - mipi_dsi_dcs_read() w/ accum_err + * @ctx: Context for multiple DSI transactions + * @cmd: DCS command + * @data: buffer in which to receive data + * @len: size of receive buffer + * + * Like mipi_dsi_dcs_read() but deals with errors in a way that makes it + * convenient to make several calls in a row. + */ +void mipi_dsi_dcs_read_multi(struct mipi_dsi_multi_context *ctx, u8 cmd, + void *data, size_t len) +{ + struct mipi_dsi_device *dsi =3D ctx->dsi; + struct device *dev =3D &dsi->dev; + struct mipi_dsi_msg msg =3D { + .channel =3D dsi->channel, + .type =3D MIPI_DSI_DCS_READ, + .tx_buf =3D &cmd, + .tx_len =3D 1, + .rx_buf =3D data, + .rx_len =3D len + }; + ssize_t ret; + + if (ctx->accum_err) + return; + + ret =3D mipi_dsi_device_transfer(dsi, &msg); + if (ret < 0) { + ctx->accum_err =3D ret; + dev_err(dev, "dcs read with command %#x failed: %d\n", cmd, + ctx->accum_err); + } +} +EXPORT_SYMBOL(mipi_dsi_dcs_read_multi); + /** * mipi_dsi_dcs_nop() - send DCS nop packet * @dsi: DSI peripheral device diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h index 369b0d8830c3..bfee4071e89e 100644 --- a/include/drm/drm_mipi_dsi.h +++ b/include/drm/drm_mipi_dsi.h @@ -333,6 +333,8 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi,= u8 cmd, const void *data, size_t len); ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data, size_t len); +void mipi_dsi_dcs_read_multi(struct mipi_dsi_multi_context *ctx, u8 cmd, + void *data, size_t len); int mipi_dsi_dcs_nop(struct mipi_dsi_device *dsi); int mipi_dsi_dcs_soft_reset(struct mipi_dsi_device *dsi); int mipi_dsi_dcs_get_power_mode(struct mipi_dsi_device *dsi, u8 *mode); @@ -415,6 +417,22 @@ void mipi_dsi_dcs_set_tear_off_multi(struct mipi_dsi_m= ulti_context *ctx); mipi_dsi_generic_write_multi(ctx, d, ARRAY_SIZE(d)); \ } while (0) =20 +/** + * mipi_dsi_generic_write_var_seq_multi - transmit non-static data using a + * generic write packet + * + * This macro will print errors for you and error handling is optimized for + * callers that call this multiple times in a row. + * + * @ctx: Context for multiple DSI transactions + * @seq: buffer containing the payload + */ +#define mipi_dsi_generic_write_var_seq_multi(ctx, seq...) \ + do { \ + const u8 d[] =3D { seq }; \ + mipi_dsi_generic_write_multi(ctx, d, ARRAY_SIZE(d)); \ + } while (0) + /** * mipi_dsi_dcs_write_seq_multi - transmit a DCS command with payload * @@ -431,6 +449,23 @@ void mipi_dsi_dcs_set_tear_off_multi(struct mipi_dsi_m= ulti_context *ctx); mipi_dsi_dcs_write_buffer_multi(ctx, d, ARRAY_SIZE(d)); \ } while (0) =20 +/** + * mipi_dsi_dcs_write_var_seq_multi - transmit a DCS command with non-stat= ic + * payload + * + * This macro will print errors for you and error handling is optimized for + * callers that call this multiple times in a row. + * + * @ctx: Context for multiple DSI transactions + * @cmd: Command + * @seq: buffer containing data to be transmitted + */ +#define mipi_dsi_dcs_write_var_seq_multi(ctx, cmd, seq...) \ + do { \ + const u8 d[] =3D { cmd, seq }; \ + mipi_dsi_dcs_write_buffer_multi(ctx, d, ARRAY_SIZE(d)); \ + } while (0) + /** * struct mipi_dsi_driver - DSI driver * @driver: device driver model driver --=20 2.50.1 From nobody Sun Oct 5 21:59:56 2025 Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) (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 55AF1246BAF for ; 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Mon, 28 Jul 2025 22:44:51 -0700 (PDT) Received: from mystery-machine.tail542cf.ts.net ([64.71.154.6]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7640872a500sm6972462b3a.22.2025.07.28.22.44.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Jul 2025 22:44:50 -0700 (PDT) From: Brigham Campbell To: maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, linus.walleij@linaro.org, neil.armstrong@linaro.org, jessica.zhang@oss.qualcomm.com, sam@ravnborg.org Cc: dianders@chromium.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Brigham Campbell Subject: [PATCH v2 3/3] drm/panel: novatek-nt35560: Clean up driver Date: Mon, 28 Jul 2025 23:44:35 -0600 Message-ID: <20250729054435.1209156-4-me@brighamcampbell.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250729054435.1209156-1-me@brighamcampbell.com> References: <20250729054435.1209156-1-me@brighamcampbell.com> 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" Update driver to use the "multi" variants of MIPI functions which facilitate improved error handling and cleaner driver code. Remove information from a comment which was made obsolete by commit 994ea402c767 ("drm/panel: Rename Sony ACX424 to Novatek NT35560"), which determined that this driver supports the Novatek NT35560 panel controller. Signed-off-by: Brigham Campbell Reviewed-by: Douglas Anderson --- drivers/gpu/drm/panel/panel-novatek-nt35560.c | 198 ++++++------------ 1 file changed, 60 insertions(+), 138 deletions(-) diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35560.c b/drivers/gpu/dr= m/panel/panel-novatek-nt35560.c index 17898a29efe8..561e6643dcbb 100644 --- a/drivers/gpu/drm/panel/panel-novatek-nt35560.c +++ b/drivers/gpu/drm/panel/panel-novatek-nt35560.c @@ -148,24 +148,20 @@ static inline struct nt35560 *panel_to_nt35560(struct= drm_panel *panel) static int nt35560_set_brightness(struct backlight_device *bl) { struct nt35560 *nt =3D bl_get_data(bl); - struct mipi_dsi_device *dsi =3D to_mipi_dsi_device(nt->dev); - int period_ns =3D 1023; + struct mipi_dsi_multi_context dsi_ctx =3D { + .dsi =3D to_mipi_dsi_device(nt->dev) + }; int duty_ns =3D bl->props.brightness; + int period_ns =3D 1023; u8 pwm_ratio; u8 pwm_div; - u8 par; - int ret; =20 if (backlight_is_blank(bl)) { /* Disable backlight */ - par =3D 0x00; - ret =3D mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY, - &par, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to disable display backlight (%d)\n", ret); - return ret; - } - return 0; + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, + MIPI_DCS_WRITE_CONTROL_DISPLAY, + 0x00); + return dsi_ctx.accum_err; } =20 /* Calculate the PWM duty cycle in n/256's */ @@ -176,12 +172,6 @@ static int nt35560_set_brightness(struct backlight_dev= ice *bl) =20 /* Set up PWM dutycycle ONE byte (differs from the standard) */ dev_dbg(nt->dev, "calculated duty cycle %02x\n", pwm_ratio); - ret =3D mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS, - &pwm_ratio, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to set display PWM ratio (%d)\n", ret); - return ret; - } =20 /* * Sequence to write PWMDIV: @@ -192,46 +182,23 @@ static int nt35560_set_brightness(struct backlight_de= vice *bl) * 0x22 PWMDIV * 0x7F 0xAA CMD2 page 1 lock */ - par =3D 0xaa; - ret =3D mipi_dsi_dcs_write(dsi, 0xf3, &par, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to unlock CMD 2 (%d)\n", ret); - return ret; - } - par =3D 0x01; - ret =3D mipi_dsi_dcs_write(dsi, 0x00, &par, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to enter page 1 (%d)\n", ret); - return ret; - } - par =3D 0x01; - ret =3D mipi_dsi_dcs_write(dsi, 0x7d, &par, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to disable MTP reload (%d)\n", ret); - return ret; - } - ret =3D mipi_dsi_dcs_write(dsi, 0x22, &pwm_div, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to set PWM divisor (%d)\n", ret); - return ret; - } - par =3D 0xaa; - ret =3D mipi_dsi_dcs_write(dsi, 0x7f, &par, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to lock CMD 2 (%d)\n", ret); - return ret; - } + mipi_dsi_dcs_write_var_seq_multi(&dsi_ctx, + MIPI_DCS_SET_DISPLAY_BRIGHTNESS, + pwm_ratio); + + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf3, 0xaa); + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x00, 0x01); + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x7d, 0x01); + + mipi_dsi_dcs_write_var_seq_multi(&dsi_ctx, 0x22, pwm_div); + + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x7f, 0xaa); =20 /* Enable backlight */ - par =3D 0x24; - ret =3D mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY, - &par, 1); - if (ret < 0) { - dev_err(nt->dev, "failed to enable display backlight (%d)\n", ret); - return ret; - } + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, MIPI_DCS_WRITE_CONTROL_DISPLAY, + 0x24); =20 - return 0; + return dsi_ctx.accum_err; } =20 static const struct backlight_ops nt35560_bl_ops =3D { @@ -244,32 +211,23 @@ static const struct backlight_properties nt35560_bl_p= rops =3D { .max_brightness =3D 1023, }; =20 -static int nt35560_read_id(struct nt35560 *nt) +static void nt35560_read_id(struct mipi_dsi_multi_context *dsi_ctx) { - struct mipi_dsi_device *dsi =3D to_mipi_dsi_device(nt->dev); + struct device dev =3D dsi_ctx->dsi->dev; u8 vendor, version, panel; u16 val; - int ret; =20 - ret =3D mipi_dsi_dcs_read(dsi, NT35560_DCS_READ_ID1, &vendor, 1); - if (ret < 0) { - dev_err(nt->dev, "could not vendor ID byte\n"); - return ret; - } - ret =3D mipi_dsi_dcs_read(dsi, NT35560_DCS_READ_ID2, &version, 1); - if (ret < 0) { - dev_err(nt->dev, "could not read device version byte\n"); - return ret; - } - ret =3D mipi_dsi_dcs_read(dsi, NT35560_DCS_READ_ID3, &panel, 1); - if (ret < 0) { - dev_err(nt->dev, "could not read panel ID byte\n"); - return ret; - } + mipi_dsi_dcs_read_multi(dsi_ctx, NT35560_DCS_READ_ID1, &vendor, 1); + mipi_dsi_dcs_read_multi(dsi_ctx, NT35560_DCS_READ_ID2, &version, 1); + mipi_dsi_dcs_read_multi(dsi_ctx, NT35560_DCS_READ_ID3, &panel, 1); + + if (dsi_ctx->accum_err < 0) + return; =20 if (vendor =3D=3D 0x00) { - dev_err(nt->dev, "device vendor ID is zero\n"); - return -ENODEV; + dev_err(&dev, "device vendor ID is zero\n"); + dsi_ctx->accum_err =3D -ENODEV; + return; } =20 val =3D (vendor << 8) | panel; @@ -278,16 +236,16 @@ static int nt35560_read_id(struct nt35560 *nt) case DISPLAY_SONY_ACX424AKP_ID2: case DISPLAY_SONY_ACX424AKP_ID3: case DISPLAY_SONY_ACX424AKP_ID4: - dev_info(nt->dev, "MTP vendor: %02x, version: %02x, panel: %02x\n", + dev_info(&dev, + "MTP vendor: %02x, version: %02x, panel: %02x\n", vendor, version, panel); break; default: - dev_info(nt->dev, "unknown vendor: %02x, version: %02x, panel: %02x\n", + dev_info(&dev, + "unknown vendor: %02x, version: %02x, panel: %02x\n", vendor, version, panel); break; } - - return 0; } =20 static int nt35560_power_on(struct nt35560 *nt) @@ -322,92 +280,56 @@ static void nt35560_power_off(struct nt35560 *nt) static int nt35560_prepare(struct drm_panel *panel) { struct nt35560 *nt =3D panel_to_nt35560(panel); - struct mipi_dsi_device *dsi =3D to_mipi_dsi_device(nt->dev); - const u8 mddi =3D 3; + struct mipi_dsi_multi_context dsi_ctx =3D { + .dsi =3D to_mipi_dsi_device(nt->dev) + }; int ret; =20 ret =3D nt35560_power_on(nt); if (ret) return ret; =20 - ret =3D nt35560_read_id(nt); - if (ret) { - dev_err(nt->dev, "failed to read panel ID (%d)\n", ret); - goto err_power_off; - } + nt35560_read_id(&dsi_ctx); =20 - /* Enabe tearing mode: send TE (tearing effect) at VBLANK */ - ret =3D mipi_dsi_dcs_set_tear_on(dsi, + /* Enable tearing mode: send TE (tearing effect) at VBLANK */ + mipi_dsi_dcs_set_tear_on_multi(&dsi_ctx, MIPI_DSI_DCS_TEAR_MODE_VBLANK); - if (ret) { - dev_err(nt->dev, "failed to enable vblank TE (%d)\n", ret); - goto err_power_off; - } =20 /* * Set MDDI * * This presumably deactivates the Qualcomm MDDI interface and * selects DSI, similar code is found in other drivers such as the - * Sharp LS043T1LE01 which makes us suspect that this panel may be - * using a Novatek NT35565 or similar display driver chip that shares - * this command. Due to the lack of documentation we cannot know for - * sure. + * Sharp LS043T1LE01. */ - ret =3D mipi_dsi_dcs_write(dsi, NT35560_DCS_SET_MDDI, - &mddi, sizeof(mddi)); - if (ret < 0) { - dev_err(nt->dev, "failed to set MDDI (%d)\n", ret); - goto err_power_off; - } + mipi_dsi_dcs_write_seq_multi(&dsi_ctx, NT35560_DCS_SET_MDDI, 3); =20 - /* Exit sleep mode */ - ret =3D mipi_dsi_dcs_exit_sleep_mode(dsi); - if (ret) { - dev_err(nt->dev, "failed to exit sleep mode (%d)\n", ret); - goto err_power_off; - } - msleep(140); + mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx); + mipi_dsi_msleep(&dsi_ctx, 140); =20 - ret =3D mipi_dsi_dcs_set_display_on(dsi); - if (ret) { - dev_err(nt->dev, "failed to turn display on (%d)\n", ret); - goto err_power_off; - } + mipi_dsi_dcs_set_display_on_multi(&dsi_ctx); if (nt->video_mode) { - /* In video mode turn peripheral on */ - ret =3D mipi_dsi_turn_on_peripheral(dsi); - if (ret) { - dev_err(nt->dev, "failed to turn on peripheral\n"); - goto err_power_off; - } + mipi_dsi_turn_on_peripheral_multi(&dsi_ctx); } =20 - return 0; - -err_power_off: - nt35560_power_off(nt); - return ret; + if (dsi_ctx.accum_err < 0) + nt35560_power_off(nt); + return dsi_ctx.accum_err; } =20 static int nt35560_unprepare(struct drm_panel *panel) { struct nt35560 *nt =3D panel_to_nt35560(panel); - struct mipi_dsi_device *dsi =3D to_mipi_dsi_device(nt->dev); - int ret; + struct mipi_dsi_multi_context dsi_ctx =3D { + .dsi =3D to_mipi_dsi_device(nt->dev) + }; =20 - ret =3D mipi_dsi_dcs_set_display_off(dsi); - if (ret) { - dev_err(nt->dev, "failed to turn display off (%d)\n", ret); - return ret; - } + mipi_dsi_dcs_set_display_off_multi(&dsi_ctx); + mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx); + + if (dsi_ctx.accum_err < 0) + return dsi_ctx.accum_err; =20 - /* Enter sleep mode */ - ret =3D mipi_dsi_dcs_enter_sleep_mode(dsi); - if (ret) { - dev_err(nt->dev, "failed to enter sleep mode (%d)\n", ret); - return ret; - } msleep(85); =20 nt35560_power_off(nt); --=20 2.50.1