diff mbox series

[v3,12/25] drm/sun4i: sun6i_mipi_dsi: Add DSI hblk packet overhead

Message ID 20181026144344.27778-13-jagan@amarulasolutions.com
State Superseded
Headers show
Series drm/sun4i: Allwinner A64 MIPI-DSI support | expand

Commit Message

Jagan Teki Oct. 26, 2018, 2:43 p.m. UTC
Add 10 bytes packet overhead for hblk where blank is set using
a blanking packet like (4 bytes + 4 bytes + payload + 2 bytes)

This is according to BSP code from BPI-M64-bsp
(in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
dsi_hblk = (ht-hspw)*dsi_pixel_bits[format]/8-(4+4+2);

So, add 10 bytes packet overhead for DSI hblk.

Tested on 2-lane, 4-lane MIPI-DSI LCD panels.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>
---
Changes for v3:
- new patch
Changes for v2:
- none

 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Comments

Maxime Ripard Oct. 29, 2018, 9:22 a.m. UTC | #1
On Fri, Oct 26, 2018 at 08:13:31PM +0530, Jagan Teki wrote:
> Add 10 bytes packet overhead for hblk where blank is set using
> a blanking packet like (4 bytes + 4 bytes + payload + 2 bytes)
> 
> This is according to BSP code from BPI-M64-bsp
> (in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
> dsi_hblk = (ht-hspw)*dsi_pixel_bits[format]/8-(4+4+2);
> 
> So, add 10 bytes packet overhead for DSI hblk.
> 
> Tested on 2-lane, 4-lane MIPI-DSI LCD panels.
> 
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> Tested-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> Changes for v3:
> - new patch
> Changes for v2:
> - none
> 
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index 596e560263bf..cf42be1f1ba1 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> @@ -461,7 +461,7 @@ 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;
> +	u16 hbp, hfp, hsa, hblk_max, hblk, vblk;
>  	size_t bytes;
>  	u8 *buffer;
>  
> @@ -494,8 +494,13 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
>  
>  	/*
>  	 * 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
>  	 */
> -	hblk = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
> +#define HBLK_PACKET_OVERHEAD	10
> +	hblk_max = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
> +	hblk_max -= HBLK_PACKET_OVERHEAD;
> +	hblk = max((unsigned int)HBLK_PACKET_OVERHEAD, hblk_max);

I'd rather use the same convention than the other assignments done
before in that function.

Maxime
Jagan Teki Oct. 29, 2018, 2:26 p.m. UTC | #2
On Mon, Oct 29, 2018 at 2:52 PM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
>
> On Fri, Oct 26, 2018 at 08:13:31PM +0530, Jagan Teki wrote:
> > Add 10 bytes packet overhead for hblk where blank is set using
> > a blanking packet like (4 bytes + 4 bytes + payload + 2 bytes)
> >
> > This is according to BSP code from BPI-M64-bsp
> > (in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
> > dsi_hblk = (ht-hspw)*dsi_pixel_bits[format]/8-(4+4+2);
> >
> > So, add 10 bytes packet overhead for DSI hblk.
> >
> > Tested on 2-lane, 4-lane MIPI-DSI LCD panels.
> >
> > Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> > Tested-by: Jagan Teki <jagan@amarulasolutions.com>
> > ---
> > Changes for v3:
> > - new patch
> > Changes for v2:
> > - none
> >
> >  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > index 596e560263bf..cf42be1f1ba1 100644
> > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > @@ -461,7 +461,7 @@ 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;
> > +     u16 hbp, hfp, hsa, hblk_max, hblk, vblk;
> >       size_t bytes;
> >       u8 *buffer;
> >
> > @@ -494,8 +494,13 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
> >
> >       /*
> >        * 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
> >        */
> > -     hblk = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
> > +#define HBLK_PACKET_OVERHEAD 10
> > +     hblk_max = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
> > +     hblk_max -= HBLK_PACKET_OVERHEAD;
> > +     hblk = max((unsigned int)HBLK_PACKET_OVERHEAD, hblk_max);
>
> I'd rather use the same convention than the other assignments done
> before in that function.

Yes, old code did use hsa. but it's added 10 bytes packet head instead
of subtracting it.

hblk = mode->htotal * Bpp - hsa;
=> mode->htotal * Bpp - (mode->hsync_end - mode->hsync_start) * Bpp -
HSA_PACKET_OVERHEAD);
=> (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp +
HSA_PACKET_OVERHEAD;

And it should be
(mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp -
HSA_PACKET_OVERHEAD;

This patch is simply doing the same by explicitly adding packet over
ahead macro, which again used in hfp.
Maxime Ripard Nov. 5, 2018, 8:31 a.m. UTC | #3
On Mon, Oct 29, 2018 at 07:56:27PM +0530, Jagan Teki wrote:
> On Mon, Oct 29, 2018 at 2:52 PM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> >
> > On Fri, Oct 26, 2018 at 08:13:31PM +0530, Jagan Teki wrote:
> > > Add 10 bytes packet overhead for hblk where blank is set using
> > > a blanking packet like (4 bytes + 4 bytes + payload + 2 bytes)
> > >
> > > This is according to BSP code from BPI-M64-bsp
> > > (in drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c)
> > > dsi_hblk = (ht-hspw)*dsi_pixel_bits[format]/8-(4+4+2);
> > >
> > > So, add 10 bytes packet overhead for DSI hblk.
> > >
> > > Tested on 2-lane, 4-lane MIPI-DSI LCD panels.
> > >
> > > Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> > > Tested-by: Jagan Teki <jagan@amarulasolutions.com>
> > > ---
> > > Changes for v3:
> > > - new patch
> > > Changes for v2:
> > > - none
> > >
> > >  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 9 +++++++--
> > >  1 file changed, 7 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > > index 596e560263bf..cf42be1f1ba1 100644
> > > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > > @@ -461,7 +461,7 @@ 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;
> > > +     u16 hbp, hfp, hsa, hblk_max, hblk, vblk;
> > >       size_t bytes;
> > >       u8 *buffer;
> > >
> > > @@ -494,8 +494,13 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
> > >
> > >       /*
> > >        * 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
> > >        */
> > > -     hblk = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
> > > +#define HBLK_PACKET_OVERHEAD 10
> > > +     hblk_max = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
> > > +     hblk_max -= HBLK_PACKET_OVERHEAD;
> > > +     hblk = max((unsigned int)HBLK_PACKET_OVERHEAD, hblk_max);
> >
> > I'd rather use the same convention than the other assignments done
> > before in that function.
> 
> Yes, old code did use hsa. but it's added 10 bytes packet head instead
> of subtracting it.
> 
> hblk = mode->htotal * Bpp - hsa;
> => mode->htotal * Bpp - (mode->hsync_end - mode->hsync_start) * Bpp -
> HSA_PACKET_OVERHEAD);
> => (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp +
> HSA_PACKET_OVERHEAD;
> 
> And it should be
> (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp -
> HSA_PACKET_OVERHEAD;
> 
> This patch is simply doing the same by explicitly adding packet over
> ahead macro, which again used in hfp.

That's not my point.

The rest of the driver uses a construct that would be:

hblk = max((unsigned int)HBLK_PACKET_OVERHEAD,
           (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp - HBLK_PACKET_OVERHEAD);

We want to remain consistent.

Maxime
diff mbox series

Patch

diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
index 596e560263bf..cf42be1f1ba1 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
@@ -461,7 +461,7 @@  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;
+	u16 hbp, hfp, hsa, hblk_max, hblk, vblk;
 	size_t bytes;
 	u8 *buffer;
 
@@ -494,8 +494,13 @@  static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
 
 	/*
 	 * 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
 	 */
-	hblk = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
+#define HBLK_PACKET_OVERHEAD	10
+	hblk_max = (mode->htotal - (mode->hsync_end - mode->hsync_start)) * Bpp;
+	hblk_max -= HBLK_PACKET_OVERHEAD;
+	hblk = max((unsigned int)HBLK_PACKET_OVERHEAD, hblk_max);
 
 	/*
 	 * And I'm not entirely sure what vblk is about. The driver in