[PATCH 03/10] drm/sun4i: sun6i_mipi_dsi: Setup burst mode timings

Maxime Ripard
2018-11-05T10:40:13Z

On Sat, Nov 03, 2018 at 03:38:53PM +0530, Jagan Teki wrote:
> Burst mode display timings are different from convectional
> video mode so update the horizontal and vertical timings.
>
> Reference code taken from BSP
> (in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
> dsi_hsa = 0;
> dsi_hbp = 0;
> dsi_hact = x*dsi_pixel_bits[format]/8;
> dsi_hblk = dsi_hact;
> dsi_hfp = 0;
> dsi_vblk = 0;
>
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 108 ++++++++++++++-----------
> 1 file changed, 60 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index 077b57ec964c..4965b2c71e4c 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> @@ -479,59 +479,71 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
>
> /* 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;
> + hblk = mode->hdisplay * Bpp;
> + hfp = 0;
> + vblk = 0;
> + } 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);
> -
> - /*
> - * hblk seems to be the line + porches length.
> - * The blank is set using a blanking packet (4 bytes + 4 bytes +
> - * payload + 2 bytes). So minimal size is 10 bytes
> - */
> + hbp = max((unsigned int)HBP_PACKET_OVERHEAD,
> + (mode->htotal - mode->hsync_end) * Bpp -
> + HBP_PACKET_OVERHEAD);
> +
> + /*
> + * hblk seems to be the line + porches length.
> + * The blank is set using a blanking packet (4 bytes + 4 bytes
> + * + payload + 2 bytes). So minimal size is 10 bytes
> + */
> #define HBLK_PACKET_OVERHEAD 10
> - hblk_max = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
> - hblk_max -= HBLK_PACKET_OVERHEAD;
> - hblk = max_t(unsigned int, HBLK_PACKET_OVERHEAD, hblk_max);
> -
> - /*
> - * The frontporch is set using a blanking packet (4 bytes +
> - * payload + 2 bytes). Its minimal size is therefore 6 bytes
> - *
> - * According to BSP code, extra 10 bytes(which is hblk packet overhead)
> - * is adding for hfp packet overhead since hfp depends on hblk.
> - */
> + hblk_max = (mode->htotal -
> + (mode->hsync_end - mode->hsync_start)) * Bpp;
> + hblk_max -= HBLK_PACKET_OVERHEAD;
> + hblk = max_t(unsigned int, HBLK_PACKET_OVERHEAD, hblk_max);
> +
> + /*
> + * The frontporch is set using a blanking packet (4 bytes +
> + * payload + 2 bytes). Its minimal size is therefore 6 bytes
> + *
> + * According to BSP code, extra 10 bytes(which is hblk packet
> + * overhead) is adding for hfp packet overhead since hfp
> + * depends on hblk.
> + */
> #define HFP_PACKET_OVERHEAD 6
> - hfp_pkt_overhead = (HFP_PACKET_OVERHEAD + HBLK_PACKET_OVERHEAD);
> - hfp = max((unsigned int)hfp_pkt_overhead,
> - (mode->hsync_start - mode->hdisplay) * Bpp -
> - hfp_pkt_overhead);
> -
> - /*
> - * The vertical blank is set using a blanking packet (4 bytes +
> - * payload + 2 bytes). Its minimal size is therefore 6 bytes
> - */
> + hfp_pkt_overhead = (HFP_PACKET_OVERHEAD + HBLK_PACKET_OVERHEAD);
> + hfp = max((unsigned int)hfp_pkt_overhead,
> + (mode->hsync_start - mode->hdisplay) * Bpp -
> + hfp_pkt_overhead);
> +
> + /*
> + * The vertical blank is set using a blanking packet (4 bytes +
> + * payload + 2 bytes). Its minimal size is therefore 6 bytes
> + */
> #define VBLK_PACKET_OVERHEAD 6
> - if (device->lanes == 4) {
> - int tmp;
> -
> - tmp = (mode->htotal * Bpp) * mode->vtotal -
> - (hblk + VBLK_PACKET_OVERHEAD);
> - vblk = (device->lanes - tmp % device->lanes);
> - } else {
> - vblk = 0;
> + if (device->lanes == 4) {
> + int tmp;
> +
> + tmp = (mode->htotal * Bpp) * mode->vtotal -
> + (hblk + VBLK_PACKET_OVERHEAD);
> + vblk = (device->lanes - tmp % device->lanes);
> + } else {
> + vblk = 0;
> + }
> }

We should make this a couple of functions to make things more
readable.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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