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Date:   Wed, 2 Aug 2023 14:37:03 +0200
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From:   Neil Armstrong <neil.armstrong@linaro.org>
Reply-To: neil.armstrong@linaro.org
Subject: Re: [PATCH] Revert "drm/bridge: lt9611: Do not generate HFP/HBP/HSA
 and EOT packet"
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To:     Marek Vasut <marex@denx.de>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Robert Foss <rfoss@kernel.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Jagan Teki <jagan@amarulasolutions.com>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Abhinav Kumar <quic_abhinavk@quicinc.com>,
        Amit Pundir <amit.pundir@linaro.org>
References: <20230802-revert-do-not-generate-hfp-hbp-hsa-eot-packet-v1-1-f8a20084e15a@linaro.org>
 <6cd079a4-2f5b-0169-cbaf-b59a72f1b32b@denx.de>
 <084ca94e-d694-878e-0646-f4c89043cd28@denx.de>
Organization: Linaro Developer Services
In-Reply-To: <084ca94e-d694-878e-0646-f4c89043cd28@denx.de>
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On 02/08/2023 14:28, Marek Vasut wrote:
> On 8/2/23 14:07, Marek Vasut wrote:
>> On 8/2/23 10:52, Neil Armstrong wrote:
>>> This reverts commit [1] to fix display regression on the Dragonboard 845c
>>> (SDM845) devboard.
>>>
>>> There's a mismatch on the real action of the following flags:
>>> - MIPI_DSI_MODE_VIDEO_NO_HSA
>>> - MIPI_DSI_MODE_VIDEO_NO_HFP
>>> - MIPI_DSI_MODE_VIDEO_NO_HBP
>>> which leads to a non-working display on qcom platforms.
>>>
>>> [1] 8ddce13ae696 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA and EOT packet")
>>>
>>> Cc: Marek Vasut <marex@denx.de>
>>> Cc: Robert Foss <rfoss@kernel.org>
>>> Cc: Jagan Teki <jagan@amarulasolutions.com>
>>> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>>> Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
>>> Fixes: 8ddce13ae69 ("drm/bridge: lt9611: Do not generate HFP/HBP/HSA and EOT packet")
>>> Reported-by: Amit Pundir <amit.pundir@linaro.org>
>>> Link: https://lore.kernel.org/r/CAMi1Hd0TD=2z_=bcDrht3H_wiLvAFcv8Z-U_r_KUOoeMc6UMjw@mail.gmail.com/
>>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>>
>> This breaks LT9611 operation on i.MX8M Mini/Nano/Plus, so, NAK.
>>
>> I am currently using this LT9611 with Linux 6.1.y
> 
> Correction, 6.1.y only with the DSIM patches backported.

Well you'll need to keep [1] backported on your downstream branch,
this revert won't propagate to v6.1 stable anyway.

> 
>> in production and this is not acceptable. I also believe the correct fix is on the MSM side, not on the LT9611 driver side, since MSM incorrectly implements these flags.
> 

Since [1] breaks Qcom boards on v6.5, and [1] was added for v6.5 to make the bridge work
on i.MX8M Mini/Nano/Plus, it's not acceptable either to keep it for the v6.5 release.

Neil