Re: [PATCH] drm: mediatek: mtk_dsi: Fix NO_EOT_PACKET settings/handling

[Alexandre Mergnat]

On 23/06/2023 11:47, AngeloGioacchino Del Regno wrote:
> Il 23/05/23 12:42, AngeloGioacchino Del Regno ha scritto:
> > Due to the initial confusion about MIPI_DSI_MODE_EOT_PACKET, properly
> > renamed to MIPI_DSI_MODE_NO_EOT_PACKET, reflecting its actual meaning,
> > both the DSI_TXRX_CON register setting for bit (HSTX_)DIS_EOT and the
> > later calculation for horizontal sync-active (HSA), back (HBP) and
> > front (HFP) porches got incorrect due to the logic being inverted.
> >
> > This means that a number of settings were wrong because....:
> >   - DSI_TXRX_CON register setting: bit (HSTX_)DIS_EOT should be
> >     set in order to disable the End of Transmission packet;
> >   - Horizontal Sync and Back/Front porches: The delta used to
> >     calculate all of HSA, HBP and HFP should account for the
> >     additional EOT packet.
> >
> > Before this change...
> >   - Bit (HSTX_)DIS_EOT was being set when EOT packet was enabled;
> >   - For HSA/HBP/HFP delta... all three were wrong, as words were
> >     added when EOT disabled, instead of when EOT packet enabled!
> >
> > Invert the logic around flag MIPI_DSI_MODE_NO_EOT_PACKET in the
> > MediaTek DSI driver to fix the aforementioned issues.
> >
> > Fixes: 8b2b99fd7931 ("drm/mediatek: dsi: Fine tune the line time 
> > caused by EOTp")
> > Fixes: 2d52bfba09d1 ("drm/mediatek: add non-continuous clock mode and 
> > EOT packet control")
> > Signed-off-by: AngeloGioacchino Del Regno 
> > <angelogioacchino.delregno@xxxxxxxxxxxxx>
>
> Gentle ping for an important fix.
>
> Regards,
> Angelo
>
> > ---
> >   drivers/gpu/drm/mediatek/mtk_dsi.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c 
> > b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > index 7d5250351193..b0ab38e59db9 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > @@ -407,7 +407,7 @@ static void mtk_dsi_rxtx_control(struct mtk_dsi *dsi)
> >       if (dsi->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS)
> >           tmp_reg |= HSTX_CKLP_EN;
> > -    if (!(dsi->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET))
> > +    if (dsi->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
> >           tmp_reg |= DIS_EOT;
> >       writel(tmp_reg, dsi->regs + DSI_TXRX_CTRL);
> > @@ -484,7 +484,7 @@ static void mtk_dsi_config_vdo_timing(struct 
> > mtk_dsi *dsi)
> >                 timing->da_hs_zero + timing->da_hs_exit + 3;
> >       delta = dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST ? 18 : 12;
> > -    delta += dsi->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET ? 2 : 0;
> > +    delta += dsi->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET ? 0 : 2;
> >       horizontal_frontporch_byte = vm->hfront_porch * dsi_tmp_buf_bpp;
> >       horizontal_front_back_byte = horizontal_frontporch_byte + 
> > horizontal_backporch_byte;

Sounds logic

Reviewed-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>

--
Regards,
Alexandre