Subject: Re: [v9,1/3] drm/dsi: transfer DSI HS packets ending at the same time
To:     Rex-BC Chen <rex-bc.chen@mediatek.com>, chunkuang.hu@kernel.org,
        matthias.bgg@gmail.com, narmstrong@baylibre.com,
        robert.foss@linaro.org, andrzej.hajda@intel.com, daniel@ffwll.ch,
        airlied@linux.ie, p.zabel@pengutronix.de
Cc:     xji@analogixsemi.com, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        Project_Global_Chrome_Upstream_Group@mediatek.com,
        Jitao Shi <jitao.shi@mediatek.com>
References: <20220114092110.12137-1-rex-bc.chen@mediatek.com>
 <20220114092110.12137-2-rex-bc.chen@mediatek.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
Message-ID: <6874ebff-3b20-807d-0fa5-ba21986bb787@collabora.com>
Date:   Fri, 14 Jan 2022 10:59:16 +0100
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Il 14/01/22 10:21, Rex-BC Chen ha scritto:
> Since a HS transmission is composed of an arbitrary number
> of bytes that may not be an integer multiple of lanes, some
> lanes may run out of data before others.
> (Defined in 6.1.3 of mipi_DSI_specification_v.01-02-00)
> 
> However, for some DSI RX devices (for example, anx7625),
> there is a limitation that packet number should be the same
> on all DSI lanes. In other words, they need to end a HS at
> the same time.
> 
> Because this limitation is for some specific DSI RX devices,
> it is more reasonable to put the enable control in these
> DSI RX drivers. If DSI TX driver knows the information,
> they can adjust the setting for this situation.
> 
> Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>

Acked-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

> ---
>   include/drm/drm_mipi_dsi.h | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index 147e51b6d241..342dfe5a0874 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -137,6 +137,8 @@ struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node);
>   #define MIPI_DSI_CLOCK_NON_CONTINUOUS	BIT(10)
>   /* transmit data in low power */
>   #define MIPI_DSI_MODE_LPM		BIT(11)
> +/* transmit data ending in the same hsync for all lanes */
> +#define MIPI_DSI_HS_PKT_END_ALIGNED	BIT(12)
>   
>   enum mipi_dsi_pixel_format {
>   	MIPI_DSI_FMT_RGB888,
>