linux-kernel - Re: [PATCH v3, 1/4] drm/mediatek: Adjust the timing of mipi signal from LP00 to LP11

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Date:   Mon, 21 Mar 2022 17:36:32 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     <xinlei.lee@...iatek.com>, <chunkuang.hu@...nel.org>,
        <p.zabel@...gutronix.de>, <airlied@...ux.ie>, <daniel@...ll.ch>,
        <matthias.bgg@...il.com>
CC:     <jitao.shi@...iatek.com>, <linux-kernel@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        <linux-mediatek@...ts.infradead.org>, <rex-bc.chen@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3, 1/4] drm/mediatek: Adjust the timing of mipi signal
 from LP00 to LP11

Hi, Xinlei:

On Thu, 2022-03-17 at 15:53 +0800, xinlei.lee@...iatek.com wrote:
> From: Jitao Shi <jitao.shi@...iatek.com>
> 
> Old sequence:
> 1. Pull the MIPI signal high
> 2. Delay & Dsi_reset
> 3. Set the dsi timing register
> 4. dsi clk & lanes leave ulp mode and enter hs mode
> 
> New sequence:
> 1. Set the dsi timing register
> 2. Pull the MIPI signal high
> 3. Delay & Dsi_reset
> 4. dsi clk & lanes leave ulp mode and enter hs mode
> 
> In the new sequence 2 & 3 & 4 will be moved to dsi_enbale in later
> patch.

I think there would be one patch in 5.9 make the wrong sequence, so add
'Fixes' tag to indicate which patch make the wrong sequence. Use the
term correct/wrong instead old/new sequence.

I still do not understand what is the sequence after apply this patch?

Does the sequence is this after apply this patch?
1. Set the dsi timing register
2. Pull the MIPI signal high
3. Delay & Dsi_reset
4. dsi clk & lanes leave ulp mode and enter hs mode

Regards,
CK

> 
> Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> Signed-off-by: Xinlei Lee <xinlei.lee@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index ccb0511b9cd5..262c027d8c2f 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -649,14 +649,14 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
>  	mtk_dsi_reset_engine(dsi);
>  	mtk_dsi_phy_timconfig(dsi);
>  
> -	mtk_dsi_rxtx_control(dsi);
> -	usleep_range(30, 100);
> -	mtk_dsi_reset_dphy(dsi);
>  	mtk_dsi_ps_control_vact(dsi);
>  	mtk_dsi_set_vm_cmd(dsi);
>  	mtk_dsi_config_vdo_timing(dsi);
>  	mtk_dsi_set_interrupt_enable(dsi);
>  
> +	mtk_dsi_rxtx_control(dsi);
> +	usleep_range(30, 100);
> +	mtk_dsi_reset_dphy(dsi);
>  	mtk_dsi_clk_ulp_mode_leave(dsi);
>  	mtk_dsi_lane0_ulp_mode_leave(dsi);
>  	mtk_dsi_clk_hs_mode(dsi, 0);