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[90.182.211.1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1843d1e0bsm51322805e9.6.2026.10.08.01.24.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Oct 2026 01:24:37 -0700 (PDT) Message-ID: Date: Thu, 8 Oct 2026 10:24:36 +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 Subject: Re: [PATCH 2/4] drm/panel: st7703: move init commands to prepare() To: Marc-Olivier Champagne , Jessica Zhang , =?UTF-8?Q?Guido_G=C3=BCnther?= Cc: Ondrej Jirman , Purism Kernel Team , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Hugo Villeneuve , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Jerome Oufella , Felix Boucher , Quentin Lehoux References: <20261007201859.3709656-1-marc-olivier.champagne@savoirfairelinux.com> <20261007201859.3709656-3-marc-olivier.champagne@savoirfairelinux.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: <20261007201859.3709656-3-marc-olivier.champagne@savoirfairelinux.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/7/26 22:18, Marc-Olivier Champagne wrote: > The panel init sequence is currently sent from enable(), i.e. after > the DSI host has started the video stream. Not all DSI hosts accept > command packets in that state, so the init sequence may never reach > the panel. > > Move the init sequence to prepare(), right after the panel reset, to > ensure it is sent before the host enables the video stream. > > Since the init sequence can now fail in prepare(), power the panel > back down on error: the panel core does not call unprepare() when > prepare() fails, leaving the power supplies enabled. > > Both patterns are already used by other DSI panel drivers. > > Suggested-by: Hugo Villeneuve > Signed-off-by: Marc-Olivier Champagne > --- > drivers/gpu/drm/panel/panel-sitronix-st7703.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7703.c b/drivers/gpu/drm/panel/panel-sitronix-st7703.c > index 368c57591817..f4635a7327de 100644 > --- a/drivers/gpu/drm/panel/panel-sitronix-st7703.c > +++ b/drivers/gpu/drm/panel/panel-sitronix-st7703.c > @@ -774,8 +774,6 @@ static int st7703_enable(struct drm_panel *panel) > struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev); > struct mipi_dsi_multi_context dsi_ctx = {.dsi = dsi}; > > - ctx->desc->init_sequence(&dsi_ctx); > - > mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx); > > /* It takes the controller 120 msec to wake up after sleep. */ > @@ -784,7 +782,7 @@ static int st7703_enable(struct drm_panel *panel) > mipi_dsi_dcs_set_display_on_multi(&dsi_ctx); > > if (!dsi_ctx.accum_err) > - dev_dbg(ctx->dev, "Panel init sequence done\n"); > + dev_dbg(ctx->dev, "Panel enable done\n"); > > return dsi_ctx.accum_err; > } > @@ -819,6 +817,8 @@ static int st7703_unprepare(struct drm_panel *panel) > static int st7703_prepare(struct drm_panel *panel) > { > struct st7703 *ctx = panel_to_st7703(panel); > + struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev); > + struct mipi_dsi_multi_context dsi_ctx = {.dsi = dsi}; > int ret; > > dev_dbg(ctx->dev, "Resetting the panel\n"); > @@ -843,6 +843,18 @@ static int st7703_prepare(struct drm_panel *panel) > gpiod_set_value_cansleep(ctx->reset_gpio, 0); > usleep_range(15000, 20000); > > + ctx->desc->init_sequence(&dsi_ctx); > + > + if (dsi_ctx.accum_err) { > + gpiod_set_value_cansleep(ctx->reset_gpio, 1); > + regulator_disable(ctx->iovcc); > + regulator_disable(ctx->vcc); > + > + return dsi_ctx.accum_err; > + } > + > + dev_dbg(ctx->dev, "Panel init sequence done\n"); > + > return 0; > } > Reviewed-by: Neil Armstrong Thanks, Neil