Re: [PATCH 4/6] drm/bridge: tc358767: fix timing calculations

[Philipp Zabel <p.zabel@pengutronix.de>]

On Thu, 2017-07-27 at 15:47 +0300, Andrey Gusakov wrote:
> Fields in HTIM01 and HTIM02 regs should be even.
> Recomended thresh_dly value is max_tu_symbol.

What about the VSDELAY change? This should be mentioned in the commit
message.

> Signed-off-by: Andrey Gusakov <andrey.gusakov@cogentembedded.com>
> ---
>  drivers/gpu/drm/bridge/tc358767.c | 34 ++++++++++++++++++++--------------
>  1 file changed, 20 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
> index 4aee6178d889..c657a00af508 100644
> --- a/drivers/gpu/drm/bridge/tc358767.c
> +++ b/drivers/gpu/drm/bridge/tc358767.c
> @@ -659,6 +659,14 @@ static int tc_set_video_mode(struct tc_data *tc, struct drm_display_mode *mode)
>  	int lower_margin = mode->vsync_start - mode->vdisplay;
>  	int vsync_len = mode->vsync_end - mode->vsync_start;
>  
> +	/*
> +	 * Recommended maximum number of symbols transferred in a transfer unit:
> +	 * DIV_ROUND_UP((input active video bandwidth in bytes) * tu_size,
> +	 *              (output active video bandwidth in bytes))
> +	 * Must be less than tu_size.
> +	 */
> +	max_tu_symbol = TU_SIZE_RECOMMENDED - 1;
> +
>  	dev_dbg(tc->dev, "set mode %dx%d\n",
>  		mode->hdisplay, mode->vdisplay);
>  	dev_dbg(tc->dev, "H margin %d,%d sync %d\n",
> @@ -668,13 +676,18 @@ static int tc_set_video_mode(struct tc_data *tc, struct drm_display_mode *mode)
>  	dev_dbg(tc->dev, "total: %dx%d\n", mode->htotal, mode->vtotal);
>  
> 
> -	/* LCD Ctl Frame Size */
> -	tc_write(VPCTRL0, (0x40 << 20) /* VSDELAY */ |
> +	/*
> +	 * LCD Ctl Frame Size
> +	 * datasheet is not clear of vsdelay in case of DPI
> +	 * assume we do not need any delay when DPI is a source of
> +	 * sync signals
> +	 */
> +	tc_write(VPCTRL0, (0 << 20) /* VSDELAY */ |

VSDELAY is documented as the delay in pixel clocks between the time a
VSYNC/HSYNC Start DSI packet is received and the time HSYNC/VSYNC is
asserted in the DP output.
I assume that this field is just ignored in DPI mode.

>  		 OPXLFMT_RGB888 | FRMSYNC_DISABLED | MSF_DISABLED);
> -	tc_write(HTIM01, (left_margin << 16) |		/* H back porch */
> -			 (hsync_len << 0));		/* Hsync */
> -	tc_write(HTIM02, (right_margin << 16) |		/* H front porch */
> -			 (mode->hdisplay << 0));	/* width */
> +	tc_write(HTIM01, (ALIGN(left_margin, 2) << 16) | /* H back porch */
> +			 (ALIGN(hsync_len, 2) << 0));	 /* Hsync */
> +	tc_write(HTIM02, (ALIGN(right_margin, 2) << 16) |  /* H front porch */
> +			 (ALIGN(mode->hdisplay, 2) << 0)); /* width */
>  	tc_write(VTIM01, (upper_margin << 16) |		/* V back porch */
>  			 (vsync_len << 0));		/* Vsync */
>  	tc_write(VTIM02, (lower_margin << 16) |		/* V front porch */
> @@ -693,7 +706,7 @@ static int tc_set_video_mode(struct tc_data *tc, struct drm_display_mode *mode)
>  	/* DP Main Stream Attributes */
>  	vid_sync_dly = hsync_len + left_margin + mode->hdisplay;
>  	tc_write(DP0_VIDSYNCDELAY,
> -		 (0x003e << 16) |	/* thresh_dly */
> +		 (max_tu_symbol << 16) |	/* thresh_dly */
>  		 (vid_sync_dly << 0));
>  
>  	tc_write(DP0_TOTALVAL, (mode->vtotal << 16) | (mode->htotal));
> @@ -709,13 +722,6 @@ static int tc_set_video_mode(struct tc_data *tc, struct drm_display_mode *mode)
>  	tc_write(DPIPXLFMT, VS_POL_ACTIVE_LOW | HS_POL_ACTIVE_LOW |
>  		 DE_POL_ACTIVE_HIGH | SUB_CFG_TYPE_CONFIG1 | DPI_BPP_RGB888);
>  
> -	/*
> -	 * Recommended maximum number of symbols transferred in a transfer unit:
> -	 * DIV_ROUND_UP((input active video bandwidth in bytes) * tu_size,
> -	 *              (output active video bandwidth in bytes))
> -	 * Must be less than tu_size.
> -	 */
> -	max_tu_symbol = TU_SIZE_RECOMMENDED - 1;
>  	tc_write(DP0_MISC, (max_tu_symbol << 23) | (TU_SIZE_RECOMMENDED << 16) |
>  			   BPC_8);
>  

Otherwise,
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>

regards
Philipp

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