linux-kernel - Re: [v10,1/3] drm/dsi: transfer DSI HS packets ending at the same time

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Message-ID: <fa61312ca706a52caf2baca398f3674d80f4cd0d.camel@mediatek.com>
Date:   Tue, 25 Jan 2022 12:13:57 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     Andrzej Hajda <andrzej.hajda@...el.com>, <chunkuang.hu@...nel.org>,
        <matthias.bgg@...il.com>, <narmstrong@...libre.com>,
        <robert.foss@...aro.org>, <daniel@...ll.ch>, <airlied@...ux.ie>,
        <p.zabel@...gutronix.de>
CC:     <xji@...logixsemi.com>, <jitao.shi@...iatek.com>,
        <xinlei.lee@...iatek.com>,
        <angelogioacchino.delregno@...labora.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [v10,1/3] drm/dsi: transfer DSI HS packets ending at the same
 time

Hello David and Daniel,

This patch is including modification of include/drm/drm_mipi_dsi.h.
Could you give us some suggestions for this patch?

Thanks for your big support!

BRs,
Rex-BC Chen

On Wed, 2022-01-19 at 09:34 +0100, Andrzej Hajda wrote:
> On 19.01.2022 03:25, Rex-BC Chen wrote:
> > 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@...iatek.com>
> > Signed-off-by: Rex-BC Chen <rex-bc.chen@...iatek.com>
> > Acked-by: AngeloGioacchino Del Regno <
> > angelogioacchino.delregno@...labora.com>
> 
> Reviewed-by: Andrzej Hajda <andrzej.hajda@...el.com>
> 
> Regards
> 
> Andrzej
> 
> > ---
> >   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..51e09a1a106a 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 at the same time for all lanes within one
> > hsync */
> > +#define MIPI_DSI_HS_PKT_END_ALIGNED	BIT(12)
> >   
> >   enum mipi_dsi_pixel_format {
> >   	MIPI_DSI_FMT_RGB888,