Re: [PATCH] drm/bridge/synopsys: dsi: allows LP commands in video mode

From: Sam Ravnborg <sam@ravnborg.org>
To: Yannick Fertre <yannick.fertre@st.com>
Cc: Philippe Cornu <philippe.cornu@st.com>,
	Benjamin Gaignard <benjamin.gaignard@st.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@st.com>,
	dri-devel@lists.freedesktop.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/bridge/synopsys: dsi: allows LP commands in video mode
Date: Wed, 1 Jul 2020 17:09:45 +0200	[thread overview]
Message-ID: <20200701150945.GA669248@ravnborg.org> (raw)
In-Reply-To: <20200701145258.2782-1-yannick.fertre@st.com>

Hi Yannick.

On Wed, Jul 01, 2020 at 04:52:58PM +0200, Yannick Fertre wrote:
> From: Antonio Borneo <antonio.borneo@st.com>
> 
> Current code only sends LP commands in command mode.
> 
> Allows sending LP commands also in video mode by setting the
> proper flag in DSI_VID_MODE_CFG.
> 
> Signed-off-by: Antonio Borneo <antonio.borneo@st.com>

> Change-Id: Ib78fa37bcc7559ce63017acd6ee0bbf00c61a397
Change-Id is not used in kernel patches to my best knowledge.

> Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/linux-stm32/+/153242
> Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
> Reviewed-by: CIBUILD <smet-aci-builds@lists.codex.cro.st.com>
Reviews by humans, not machines..

> Reviewed-by: Yannick FERTRE <yannick.fertre@st.com>
> Reviewed-by: Philippe CORNU <philippe.cornu@st.com>
> Tested-by: Yannick FERTRE <yannick.fertre@st.com>
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> index d580b2aa4ce9..0cd43e7a69bb 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> @@ -367,6 +367,13 @@ static void dw_mipi_message_config(struct dw_mipi_dsi *dsi,
>  
>  	dsi_write(dsi, DSI_LPCLK_CTRL, lpm ? 0 : PHY_TXREQUESTCLKHS);
>  	dsi_write(dsi, DSI_CMD_MODE_CFG, val);
> +
> +	val = dsi_read(dsi, DSI_VID_MODE_CFG);
> +	if (lpm)
> +		val |= ENABLE_LOW_POWER_CMD;
> +	else
> +		val &= ~ENABLE_LOW_POWER_CMD;
> +	dsi_write(dsi, DSI_VID_MODE_CFG, val);
>  }

We have following code:

static void dw_mipi_dsi_set_mode(struct dw_mipi_dsi *dsi,
                                 unsigned long mode_flags)
{
        dsi_write(dsi, DSI_PWR_UP, RESET);

        if (mode_flags & MIPI_DSI_MODE_VIDEO) {
                dsi_write(dsi, DSI_MODE_CFG, ENABLE_VIDEO_MODE);
                dw_mipi_dsi_video_mode_config(dsi);
                dsi_write(dsi, DSI_LPCLK_CTRL, PHY_TXREQUESTCLKHS);
        } else {
                dsi_write(dsi, DSI_MODE_CFG, ENABLE_CMD_MODE);
        }

        dsi_write(dsi, DSI_PWR_UP, POWERUP);
}

Here DSI_MODE_CFG is used to set vidoe mode or not.

But the code snip above checks DSI_VID_MODE_CFG.
It looks inconsistent.

I do not know the HW - and just stumbled over this.

	Sam

>  
>  static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi *dsi, u32 hdr_val)
> -- 
> 2.17.1
> 
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