linux-kernel - Re: [v9,2/3] drm/mediatek: implement the DSI hs packets aligned

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Date:   Fri, 14 Jan 2022 18:20:12 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        <chunkuang.hu@...nel.org>, <matthias.bgg@...il.com>,
        <narmstrong@...libre.com>, <robert.foss@...aro.org>,
        <andrzej.hajda@...el.com>, <daniel@...ll.ch>, <airlied@...ux.ie>,
        <p.zabel@...gutronix.de>
CC:     <xji@...logixsemi.com>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        Jitao Shi <jitao.shi@...iatek.com>
Subject: Re: [v9,2/3] drm/mediatek: implement the DSI hs packets aligned

Hello AngeloGioacchino,

Thanks for your review.
I will modify this in next version.

BRs,
Rex-BC Chen

On Fri, 2022-01-14 at 10:36 +0100, AngeloGioacchino Del Regno wrote:
> Il 14/01/22 10:21, Rex-BC Chen ha scritto:
> > Some DSI RX devices require the packets on all lanes aligned at the
> > end.
> > Otherwise, there will be some issues of shift or scroll for screen.
> > 
> > Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> > Signed-off-by: Rex-BC Chen <rex-bc.chen@...iatek.com>
> 
> Hello,
> thanks for the patch! However, there's something to improve...
> 
> > ---
> >   drivers/gpu/drm/mediatek/mtk_dsi.c | 12 ++++++++++++
> >   1 file changed, 12 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > index 5d90d2eb0019..ccdda15f5a66 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > @@ -195,6 +195,8 @@ struct mtk_dsi {
> >   	struct clk *hs_clk;
> >   
> >   	u32 data_rate;
> > +	/* force dsi line end without dsi_null data */
> > +	bool hs_packet_end_aligned;
> 
> There's no need to introduce a new variable here...
> >   
> >   	unsigned long mode_flags;
> >   	enum mipi_dsi_pixel_format format;
> > @@ -500,6 +502,13 @@ static void mtk_dsi_config_vdo_timing(struct
> > mtk_dsi *dsi)
> >   		DRM_WARN("HFP + HBP less than d-phy, FPS will under
> > 60Hz\n");
> >   	}
> >   
> > +	if (dsi->hs_packet_end_aligned) {
> 
> You can simply check mode_flags here:
> 	if (dsi->mode_flags & MIPI_DSI_HS_PKT_END_ALIGNED) {
> 
> > +		horizontal_sync_active_byte =
> > roundup(horizontal_sync_active_byte, dsi->lanes) - 2;
> > +		horizontal_frontporch_byte =
> > roundup(horizontal_frontporch_byte, dsi->lanes) - 2;
> > +		horizontal_backporch_byte =
> > roundup(horizontal_backporch_byte, dsi->lanes) - 2;
> > +		horizontal_backporch_byte -= (vm->hactive *
> > dsi_tmp_buf_bpp + 2) % dsi->lanes;
> > +	}
> > +
> >   	writel(horizontal_sync_active_byte, dsi->regs + DSI_HSA_WC);
> >   	writel(horizontal_backporch_byte, dsi->regs + DSI_HBP_WC);
> >   	writel(horizontal_frontporch_byte, dsi->regs + DSI_HFP_WC);
> > @@ -794,6 +803,9 @@ static int mtk_dsi_host_attach(struct
> > mipi_dsi_host *host,
> >   	dsi->lanes = device->lanes;
> >   	dsi->format = device->format;
> >   	dsi->mode_flags = device->mode_flags;
> > +	dsi->hs_packet_end_aligned = (dsi->mode_flags &
> > +				      MIPI_DSI_HS_PKT_END_ALIGNED)
> > +				     ? true : false;
> 
> ...so there's no need for this one, either.
> 
> >   
> >   	return 0;
> >   }
> > 
> 
> Regards,
> - Angelo
>