Re: [PATCH v3 7/8] drm/sun4i: dsi: Add burst support

[Paul Kocialkowski <paul.kocialkowski@bootlin.com>]

Hi,

On Mon, 2019-02-11 at 15:41 +0100, Maxime Ripard wrote:
> From: Konstantin Sudakov <k.sudakov@integrasources.com>
> 
> The current driver doesn't support the DSI burst operation mode.
> 
> Let's add the needed quirks to make it work.
> 
> Signed-off-by: Konstantin Sudakov <k.sudakov@integrasources.com>
> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
> ---
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 171 ++++++++++++++++++++------
>  1 file changed, 132 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index e0288e7dc64e..4cb715dc9100 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c

[...]

> @@ -457,52 +531,71 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
>  	struct mipi_dsi_device *device = dsi->device;
>  	unsigned int Bpp = mipi_dsi_pixel_format_to_bpp(device->format) / 8;
>  	u16 hbp, hfp, hsa, hblk, vblk;
> +	u32 basic_ctl = 0;
>  	size_t bytes;
>  	u8 *buffer;
>  
>  	/* Do all timing calculations up front to allocate buffer space */
>  
> -	/*
> -	 * A sync period is composed of a blanking packet (4 bytes +
> -	 * payload + 2 bytes) and a sync event packet (4 bytes). Its
> -	 * minimal size is therefore 10 bytes
> -	 */
> +	if (device->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) {
> +		hsa = 0;
> +		hbp = 0;
> +		hfp = 0;
> +		hblk = mode->hdisplay * Bpp;
> +		vblk = 0;

It looks a bit strange to zero these variables here while basic_ctl is
initialized to zero when declared. I think it would be more consistent
to have these variables set to zero in the same fashion.

With that fixed:

Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

Cheers,

Paul

> +		basic_ctl = SUN6I_DSI_BASIC_CTL_VIDEO_BURST |
> +			    SUN6I_DSI_BASIC_CTL_HSA_HSE_DIS |
> +			    SUN6I_DSI_BASIC_CTL_HBP_DIS;
> +
> +		if (device->lanes == 4)
> +			basic_ctl |= SUN6I_DSI_BASIC_CTL_TRAIL_FILL |
> +				     SUN6I_DSI_BASIC_CTL_TRAIL_INV(0xc);
> +	} else {
> +		/*
> +		 * A sync period is composed of a blanking packet (4
> +		 * bytes + payload + 2 bytes) and a sync event packet
> +		 * (4 bytes). Its minimal size is therefore 10 bytes
> +		 */
>  #define HSA_PACKET_OVERHEAD	10
> -	hsa = max((unsigned int)HSA_PACKET_OVERHEAD,
> -		  (mode->hsync_end - mode->hsync_start) * Bpp - HSA_PACKET_OVERHEAD);
> -
> -	/*
> -	 * The backporch is set using a blanking packet (4 bytes +
> -	 * payload + 2 bytes). Its minimal size is therefore 6 bytes
> -	 */
> +		hsa = max((unsigned int)HSA_PACKET_OVERHEAD,
> +			  (mode->hsync_end - mode->hsync_start) * Bpp - HSA_PACKET_OVERHEAD);
> +
> +		/*
> +		 * The backporch is set using a blanking packet (4
> +		 * bytes + payload + 2 bytes). Its minimal size is
> +		 * therefore 6 bytes
> +		 */
>  #define HBP_PACKET_OVERHEAD	6
> -	hbp = max((unsigned int)HBP_PACKET_OVERHEAD,
> -		  (mode->htotal - mode->hsync_end) * Bpp - HBP_PACKET_OVERHEAD);
> -
> -	/*
> -	 * The frontporch is set using a blanking packet (4 bytes +
> -	 * payload + 2 bytes). Its minimal size is therefore 6 bytes
> -	 */
> +		hbp = max((unsigned int)HBP_PACKET_OVERHEAD,
> +			  (mode->htotal - mode->hsync_end) * Bpp - HBP_PACKET_OVERHEAD);
> +
> +		/*
> +		 * The frontporch is set using a blanking packet (4
> +		 * bytes + payload + 2 bytes). Its minimal size is
> +		 * therefore 6 bytes
> +		 */
>  #define HFP_PACKET_OVERHEAD	6
> -	hfp = max((unsigned int)HFP_PACKET_OVERHEAD,
> -		  (mode->hsync_start - mode->hdisplay) * Bpp - HFP_PACKET_OVERHEAD);
> -
> -	/*
> -	 * The blanking is set using a sync event (4 bytes) and a
> -	 * blanking packet (4 bytes + payload + 2 bytes). Its minimal
> -	 * size is therefore 10 bytes.
> -	 */
> +		hfp = max((unsigned int)HFP_PACKET_OVERHEAD,
> +			  (mode->hsync_start - mode->hdisplay) * Bpp - HFP_PACKET_OVERHEAD);
> +
> +		/*
> +		 * The blanking is set using a sync event (4 bytes)
> +		 * and a blanking packet (4 bytes + payload + 2
> +		 * bytes). Its minimal size is therefore 10 bytes.
> +		 */
>  #define HBLK_PACKET_OVERHEAD	10
> -	hblk = max((unsigned int)HBLK_PACKET_OVERHEAD,
> -		   (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp - HBLK_PACKET_OVERHEAD);
> -
> -	/*
> -	 * And I'm not entirely sure what vblk is about. The driver in
> -	 * Allwinner BSP is using a rather convoluted calculation
> -	 * there only for 4 lanes. However, using 0 (the !4 lanes
> -	 * case) even with a 4 lanes screen seems to work...
> -	 */
> -	vblk = 0;
> +		hblk = max((unsigned int)HBLK_PACKET_OVERHEAD,
> +			   (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp -
> +			   HBLK_PACKET_OVERHEAD);
> +
> +		/*
> +		 * And I'm not entirely sure what vblk is about. The driver in
> +		 * Allwinner BSP is using a rather convoluted calculation
> +		 * there only for 4 lanes. However, using 0 (the !4 lanes
> +		 * case) even with a 4 lanes screen seems to work...
> +		 */
> +		vblk = 0;
> +	}
>  
>  	/* How many bytes do we need to send all payloads? */
>  	bytes = max_t(size_t, max(max(hfp, hblk), max(hsa, hbp)), vblk);
> @@ -510,7 +603,7 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
>  	if (WARN_ON(!buffer))
>  		return;
>  
> -	regmap_write(dsi->regs, SUN6I_DSI_BASIC_CTL_REG, 0);
> +	regmap_write(dsi->regs, SUN6I_DSI_BASIC_CTL_REG, basic_ctl);
>  
>  	regmap_write(dsi->regs, SUN6I_DSI_SYNC_HSS_REG,
>  		     sun6i_dsi_build_sync_pkt(MIPI_DSI_H_SYNC_START,
-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com


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