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([2a01:e0a:3d9:2080:f77b:949e:1d61:69a8]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39eae96bf97sm1354424f8f.25.2025.04.11.01.55.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Apr 2025 01:55:56 -0700 (PDT) Message-ID: <3d0cff04-07f3-49cb-83cc-afd4f052e8d5@linaro.org> Date: Fri, 11 Apr 2025 10:55:55 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Neil Armstrong Reply-To: neil.armstrong@linaro.org Subject: Re: [PATCH 7/7] drm/panel: make prepare/enable and disable/unprepare calls return void To: Dmitry Baryshkov , Andrzej Hajda , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jessica Zhang Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20250401-panel-return-void-v1-0-93e1be33dc8d@oss.qualcomm.com> <20250401-panel-return-void-v1-7-93e1be33dc8d@oss.qualcomm.com> Content-Language: en-US, fr Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro In-Reply-To: <20250401-panel-return-void-v1-7-93e1be33dc8d@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 01/04/2025 07:11, Dmitry Baryshkov wrote: > Now there are no users of the return value of the drm_panel_prepare(), > drm_panel_unprepare(), drm_panel_enable() and drm_panel_disable() calls. > Usually these calls are performed from the atomic callbacks, where it is > impossible to return an error. Stop returning error codes and return > void instead. > > Signed-off-by: Dmitry Baryshkov > --- > drivers/gpu/drm/drm_panel.c | 54 +++++++++---------------- > drivers/gpu/drm/panel/panel-newvision-nv3051d.c | 9 +---- > include/drm/drm_panel.h | 8 ++-- > 3 files changed, 26 insertions(+), 45 deletions(-) > > diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c > index c627e42a7ce70459f50eb5095fffc806ca45dabf..faa7a76b63b53b3a45b3400d8bf3b58a027a340e 100644 > --- a/drivers/gpu/drm/drm_panel.c > +++ b/drivers/gpu/drm/drm_panel.c > @@ -105,21 +105,21 @@ EXPORT_SYMBOL(drm_panel_remove); > * > * Calling this function will enable power and deassert any reset signals to > * the panel. After this has completed it is possible to communicate with any > - * integrated circuitry via a command bus. > - * > - * Return: 0 on success or a negative error code on failure. > + * integrated circuitry via a command bus. This function cannot fail (as it is > + * called from the pre_enable call chain). There will always be a call to > + * drm_panel_disable() afterwards. > */ > -int drm_panel_prepare(struct drm_panel *panel) > +void drm_panel_prepare(struct drm_panel *panel) > { > struct drm_panel_follower *follower; > int ret; > > if (!panel) > - return -EINVAL; > + return; > > if (panel->prepared) { > dev_warn(panel->dev, "Skipping prepare of already prepared panel\n"); > - return 0; > + return; > } > > mutex_lock(&panel->follower_lock); > @@ -138,11 +138,8 @@ int drm_panel_prepare(struct drm_panel *panel) > follower->funcs->panel_prepared, ret); > } > > - ret = 0; > exit: > mutex_unlock(&panel->follower_lock); > - > - return ret; > } > EXPORT_SYMBOL(drm_panel_prepare); > > @@ -154,16 +151,14 @@ EXPORT_SYMBOL(drm_panel_prepare); > * reset, turn off power supplies, ...). After this function has completed, it > * is usually no longer possible to communicate with the panel until another > * call to drm_panel_prepare(). > - * > - * Return: 0 on success or a negative error code on failure. > */ > -int drm_panel_unprepare(struct drm_panel *panel) > +void drm_panel_unprepare(struct drm_panel *panel) > { > struct drm_panel_follower *follower; > int ret; > > if (!panel) > - return -EINVAL; > + return; > > /* > * If you are seeing the warning below it likely means one of two things: > @@ -176,7 +171,7 @@ int drm_panel_unprepare(struct drm_panel *panel) > */ > if (!panel->prepared) { > dev_warn(panel->dev, "Skipping unprepare of already unprepared panel\n"); > - return 0; > + return; > } > > mutex_lock(&panel->follower_lock); > @@ -195,11 +190,8 @@ int drm_panel_unprepare(struct drm_panel *panel) > } > panel->prepared = false; > > - ret = 0; > exit: > mutex_unlock(&panel->follower_lock); > - > - return ret; > } > EXPORT_SYMBOL(drm_panel_unprepare); > > @@ -209,26 +201,26 @@ EXPORT_SYMBOL(drm_panel_unprepare); > * > * Calling this function will cause the panel display drivers to be turned on > * and the backlight to be enabled. Content will be visible on screen after > - * this call completes. > - * > - * Return: 0 on success or a negative error code on failure. > + * this call completes. This function cannot fail (as it is called from the > + * enable call chain). There will always be a call to drm_panel_disable() > + * afterwards. > */ > -int drm_panel_enable(struct drm_panel *panel) > +void drm_panel_enable(struct drm_panel *panel) > { > int ret; > > if (!panel) > - return -EINVAL; > + return; > > if (panel->enabled) { > dev_warn(panel->dev, "Skipping enable of already enabled panel\n"); > - return 0; > + return; > } > > if (panel->funcs && panel->funcs->enable) { > ret = panel->funcs->enable(panel); > if (ret < 0) > - return ret; > + return; > } > panel->enabled = true; > > @@ -236,8 +228,6 @@ int drm_panel_enable(struct drm_panel *panel) > if (ret < 0) > DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n", > ret); > - > - return 0; > } > EXPORT_SYMBOL(drm_panel_enable); > > @@ -248,15 +238,13 @@ EXPORT_SYMBOL(drm_panel_enable); > * This will typically turn off the panel's backlight or disable the display > * drivers. For smart panels it should still be possible to communicate with > * the integrated circuitry via any command bus after this call. > - * > - * Return: 0 on success or a negative error code on failure. > */ > -int drm_panel_disable(struct drm_panel *panel) > +void drm_panel_disable(struct drm_panel *panel) > { > int ret; > > if (!panel) > - return -EINVAL; > + return; > > /* > * If you are seeing the warning below it likely means one of two things: > @@ -269,7 +257,7 @@ int drm_panel_disable(struct drm_panel *panel) > */ > if (!panel->enabled) { > dev_warn(panel->dev, "Skipping disable of already disabled panel\n"); > - return 0; > + return; > } > > ret = backlight_disable(panel->backlight); > @@ -280,11 +268,9 @@ int drm_panel_disable(struct drm_panel *panel) > if (panel->funcs && panel->funcs->disable) { > ret = panel->funcs->disable(panel); > if (ret < 0) > - return ret; > + return; > } > panel->enabled = false; > - > - return 0; > } > EXPORT_SYMBOL(drm_panel_disable); > > diff --git a/drivers/gpu/drm/panel/panel-newvision-nv3051d.c b/drivers/gpu/drm/panel/panel-newvision-nv3051d.c > index 5d115ecd5dd44c8e5e7d1fb8afe573324e987f59..b6429795e8f518646443dd8179f3ec28cef4dc0f 100644 > --- a/drivers/gpu/drm/panel/panel-newvision-nv3051d.c > +++ b/drivers/gpu/drm/panel/panel-newvision-nv3051d.c > @@ -413,15 +413,10 @@ static int panel_nv3051d_probe(struct mipi_dsi_device *dsi) > static void panel_nv3051d_shutdown(struct mipi_dsi_device *dsi) > { > struct panel_nv3051d *ctx = mipi_dsi_get_drvdata(dsi); > - int ret; > > - ret = drm_panel_unprepare(&ctx->panel); > - if (ret < 0) > - dev_err(&dsi->dev, "Failed to unprepare panel: %d\n", ret); > + drm_panel_unprepare(&ctx->panel); > > - ret = drm_panel_disable(&ctx->panel); > - if (ret < 0) > - dev_err(&dsi->dev, "Failed to disable panel: %d\n", ret); > + drm_panel_disable(&ctx->panel); > } > > static void panel_nv3051d_remove(struct mipi_dsi_device *dsi) > diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h > index a9c042c8dea1a82ef979c7a68204e0b55483fc28..18bf338c8b96254dc3f2880106b944e71ea4c9a7 100644 > --- a/include/drm/drm_panel.h > +++ b/include/drm/drm_panel.h > @@ -275,11 +275,11 @@ void drm_panel_init(struct drm_panel *panel, struct device *dev, > void drm_panel_add(struct drm_panel *panel); > void drm_panel_remove(struct drm_panel *panel); > > -int drm_panel_prepare(struct drm_panel *panel); > -int drm_panel_unprepare(struct drm_panel *panel); > +void drm_panel_prepare(struct drm_panel *panel); > +void drm_panel_unprepare(struct drm_panel *panel); > > -int drm_panel_enable(struct drm_panel *panel); > -int drm_panel_disable(struct drm_panel *panel); > +void drm_panel_enable(struct drm_panel *panel); > +void drm_panel_disable(struct drm_panel *panel); > > int drm_panel_get_modes(struct drm_panel *panel, struct drm_connector *connector); > > LGTM Reviewed-by: Neil Armstrong