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Wed, 20 May 2026 05:29:45 -0700 (PDT) Message-ID: <8a78aab6-918a-4bed-a913-05ecb559da4f@gmail.com> Date: Wed, 20 May 2026 17:59:37 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output To: Luca Ceresoli , andrzej.hajda@intel.com, neil.armstrong@linaro.org, rfoss@kernel.org Cc: Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se, jernej.skrabec@gmail.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, marex@denx.de, valentin@compulab.co.il, philippe.schenker@toradex.com, alexander.stein@ew.tq-group.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20260412053811.662461-1-tessolveupstream@gmail.com> <20260412053811.662461-2-tessolveupstream@gmail.com> <7056b23b-ed81-4d79-b782-5cfcb0102ef7@gmail.com> <60a24977-b181-40e4-bcf6-38b65af293e2@gmail.com> <1716be56-ac43-440b-a5df-58cbf571ba95@gmail.com> Content-Language: en-US From: tessolveupstream@gmail.com In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 20-05-2026 17:08, Luca Ceresoli wrote: > Hello, > > On Wed May 20, 2026 at 11:04 AM CEST, tessolveupstream wrote: > > [...] > >>>> We have not received any further updates from TI regarding this issue, and >>>> at this point, we are not sure if we will get additional feedback from them. >>>> As you had mentioned earlier that the patch could be considered after >>>> waiting for some time, could you please let us know how we can proceed >>>> further from here? >>> >>> I am getting some feedback from TI, but it is taking some time. >>> >>> For the time being I think it is clear that HBP and HFP are required, and >>> so removing the MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP >>> in your patch seems to be fully correct, even though this had no effect on >>> the panel I tested. >>> >>> I'm still trying to get some better info to ensure that switching from >>> burst mode to non-burst mode is not expected to have side effects. >>> >>> For thi reason, I think it would be great if you could send a new version >>> with two separate patches: the first one enabling HFP and HBP and which can >>> be applied right away, the second to disable burst mode for which I'd wait >>> a bit longer for TI feedback. You can keep the Tested-by lines. >>> >> >> Thanks for the clarification. I just wanted to confirm my understanding >> regarding the patch split you suggested. >> >> From your comments, my understanding is that the first patch would only >> enable HFP and HBP by removing MIPI_DSI_MODE_VIDEO_NO_HFP and >> MIPI_DSI_MODE_VIDEO_NO_HBP, while keeping burst mode enabled, so the mode >> flags would become: >> >> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | >> MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET; >> >> Then, the second patch would only disable burst mode, resulting in: >> >> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HSA | >> MIPI_DSI_MODE_NO_EOT_PACKET; >> >> Could you please confirm whether my understanding is correct? > > Yes, correct. > Thank you for the clarification. >> Also, from our testing, when using: >> >> dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | >> MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET; >> >> we are not able to get display output. > > This is the case for the panel I worked on as well. In the practice we both > observe that non-burst mode is what fixes the panel, but there is no clear > explanation of the reason in the docs (that's what I hope to discover from > TI). > > On the other hand the HBP and HFP are clearly required by the docs, so it > should be fine to enable those without waiting for further info from > TI. This is not fixing your and my panel, but it's a fix, no doubt. > >> I just wanted to mention this >> observation in case it is relevant to the patch split discussion. >> >> Additionally, regarding the Tested-by tags you mentioned earlier, >> should I carry them forward to both patches, or would you prefer them >> only on the applicable patch? > > I'd say yes. People who sent these tags have tested a patch that is the sum > of the two future patches, so I'd say it's OK to keep the R-by on both > patches. > Okay, I just wanted to confirm one point — when you mentioned R-by, are you referring to the Reviewed-by tag? I wanted to make sure I understood it correctly before carrying the tags forward in the next version. 🙂> Thanks for your patience. We'll get to the bottom of this issue! :) > > Luca > > -- > Luca Ceresoli, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com