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References: <20240417-drm-msm-initial-dualpipe-dsc-fixes-v1-0-78ae3ee9a697@somainline.org>
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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Wed, 17 Apr 2024 14:58:25 +0300
Message-ID: <CAA8EJpq-1QwoM2hEyegpfKnVH+qrswjmTd_hpYs9d9B7gikHjg@mail.gmail.com>
Subject: Re: [PATCH 2/7] drm/msm/dsi: Pass bonded-DSI hdisplay/2 to DSC timing configuration
To: Marijn Suijten <marijn.suijten@somainline.org>
Cc: Rob Clark <robdclark@gmail.com>, Abhinav Kumar <quic_abhinavk@quicinc.com>, 
	Sean Paul <sean@poorly.run>, David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
	Archit Taneja <architt@codeaurora.org>, Chandan Uddaraju <chandanu@codeaurora.org>, 
	Vinod Koul <vkoul@kernel.org>, Sravanthi Kollukuduru <skolluku@codeaurora.org>, 
	linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, 
	freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org, 
	Jordan Crouse <jordan@cosmicpenguin.net>, Rajesh Yadav <ryadav@codeaurora.org>, 
	Jeykumar Sankaran <jsanka@codeaurora.org>, ~postmarketos/upstreaming@lists.sr.ht, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, 
	Konrad Dybcio <konrad.dybcio@linaro.org>, Martin Botka <martin.botka@somainline.org>, 
	Jami Kettunen <jami.kettunen@somainline.org>
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On Wed, 17 Apr 2024 at 02:57, Marijn Suijten
<marijn.suijten@somainline.org> wrote:
>
> When configuring the timing of DSI hosts (interfaces) in
> dsi_timing_setup() all values written to registers are taking bonded
> DSI into account by dividing the original mode width by 2 (half the
> data is sent over each of the two DSI hosts), but the full width
> instead of the interface width is passed as hdisplay parameter to
> dsi_update_dsc_timing().
>
> Currently only msm_dsc_get_slices_per_intf() is called within
> dsi_update_dsc_timing() with the `hdisplay` argument which clearly
> documents that it wants the width of a single interface (which, again,
> in bonded DSI mode is half the total width of the mode).  Thus pass the
> bonded-mode-adjusted hdisplay parameter into dsi_update_dsc_timing()
> otherwise all values written to registers by this function (i.e. the
> number of slices per interface or packet, and derived from this the EOL
> byte number) are twice too large.
>
> Inversely the panel driver is expected to only set the slice width and
> number of slices for half the panel, i.e. what will be sent by each
> host individually, rather than fixing that up like hdisplay here.
>
> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration")
> Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
> ---
>  drivers/gpu/drm/msm/dsi/dsi_host.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


-- 
With best wishes
Dmitry