From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Jagan Teki <jagan@amarulasolutions.com>
Cc: Chen-Yu Tsai <wens@csie.org>, Icenowy Zheng <icenowy@aosc.io>,
Jernej Skrabec <jernej.skrabec@siol.net>,
Vasily Khoruzhick <anarsoul@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
David Airlie <airlied@linux.ie>,
dri-devel@lists.freedesktop.org,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
linux-clk@vger.kernel.org,
Michael Trimarchi <michael@amarulasolutions.com>,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com
Subject: Re: [PATCH 08/12] drm/sun4i: sun6i_mipi_dsi: Refactor vertical video start delay
Date: Thu, 27 Sep 2018 19:14:51 +0200 [thread overview]
Message-ID: <20180927171451.7iqt2nt2log5qojf@flea> (raw)
In-Reply-To: <20180927114850.24565-9-jagan@amarulasolutions.com>
On Thu, Sep 27, 2018 at 05:18:46PM +0530, Jagan Teki wrote:
> Accordingly to BPI-M64-bsp DE DSI code Video start delay
> can be computed by subtracting total vertical timing with
> front porch timing and with adding 1 delay line for TCON.
This is what the current code is doing as well.
> This patch simply add the start_delay logic from BPI-M64-bsp,
> w/o this new computation, the DSI on A64 encounter vblank time out.
>
> [CRTC:36:crtc-0] vblank wait timed out
>
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index 9918fdb990ff..217db74c6dc3 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> @@ -358,7 +358,17 @@ static void sun6i_dsi_inst_init(struct sun6i_dsi *dsi,
> static u16 sun6i_dsi_get_video_start_delay(struct sun6i_dsi *dsi,
> struct drm_display_mode *mode)
> {
> - return mode->vtotal - (mode->vsync_end - mode->vdisplay) + 1;
> + u32 vfp = mode->vsync_start - mode->vdisplay;
Again, this is wrong and contrary to what your commit log is saying.
The Allwinner code has:
u32 vfp = panel->lcd_vt - panel->lcd_y - panel->lcd_vbp;
u32 dsi_start_delay = panel->lcd_vt - vfp + 1;
So, essentially:
vtotal - (vtotal - vdisplay - back porch) + 1
The backporch is hsync_total - hsync_end, so we end up, removing the
addition / removal of vtotal, with:
vdisplay - (vsync_total - vsync_end) + 1
The formula used there looks indeed different, but unlike what you
were saying.
> + u32 start_delay;
> +
> + start_delay = mode->vtotal - vfp + 1;
> + if (start_delay > mode->vtotal)
> + start_delay -= mode->vtotal;
> +
> + if (!start_delay)
> + start_delay = 1;
> +
I guess that it's actually the clamping that fixes thing. It should be
mentionned in your commit log.
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2018-09-27 17:14 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 11:48 [PATCH 00/12] drm/sun4i: Allwinner A64 MIPI-DSI support Jagan Teki
2018-09-27 11:48 ` [PATCH 01/12] clk: sunxi-ng: a64: Fix gate bit of DSI DPHY Jagan Teki
2018-09-27 11:48 ` [PATCH 02/12] drm/sun4i: sun6i_mipi_dsi: Add Allwinner A64 MIPI DSI support Jagan Teki
2018-09-27 11:48 ` [PATCH 03/12] dt-bindings: sun6i-dsi: Add compatible for A64 MIPI DSI Jagan Teki
2018-10-15 18:24 ` Rob Herring
2018-09-27 11:48 ` [PATCH 04/12] drm/sun4i: sun6i_mipi_dsi: Enable missing DSI bus clock Jagan Teki
2018-09-27 12:42 ` Chen-Yu Tsai
2018-09-27 13:44 ` Jagan Teki
2018-09-27 14:16 ` [linux-sunxi] " Chen-Yu Tsai
2018-09-27 16:26 ` Jagan Teki
2018-09-27 16:33 ` Chen-Yu Tsai
2018-09-27 11:48 ` [PATCH 05/12] drm/sun4i: sun6i_mipi_dsi: Add DSI Generic short write 2 param transfer Jagan Teki
2018-09-27 17:18 ` Maxime Ripard
2018-09-27 17:36 ` Jagan Teki
2018-09-29 13:47 ` Maxime Ripard
2018-09-27 11:48 ` [PATCH 06/12] drm/sun4i: sun6i_mipi_dsi: Fix VBP size calculation Jagan Teki
2018-09-27 15:21 ` Maxime Ripard
2018-09-27 16:20 ` Jagan Teki
2018-09-29 13:53 ` Maxime Ripard
2018-10-01 8:09 ` [linux-sunxi] " Jagan Teki
2018-10-08 15:05 ` Maxime Ripard
2018-09-27 11:48 ` [PATCH 07/12] drm/sun4i: sun6i_mipi_dsi: Fix TCON DRQ set bits Jagan Teki
2018-09-27 16:58 ` Maxime Ripard
2018-09-27 17:45 ` Jagan Teki
2018-10-02 13:20 ` Maxime Ripard
2018-10-03 3:22 ` [linux-sunxi] " Jagan Teki
2018-10-08 15:05 ` Maxime Ripard
2018-09-27 11:48 ` [PATCH 08/12] drm/sun4i: sun6i_mipi_dsi: Refactor vertical video start delay Jagan Teki
2018-09-27 17:14 ` Maxime Ripard [this message]
2018-09-27 17:33 ` Jagan Teki
2018-09-29 15:27 ` Maxime Ripard
2018-10-01 7:55 ` [linux-sunxi] " Jagan Teki
2018-10-02 13:29 ` Maxime Ripard
2018-09-27 11:48 ` [PATCH 09/12] dt-bindings: panel: Add Bananapi S070WV20-CT16 MIPI-DSI panel bindings Jagan Teki
2018-10-15 18:24 ` Rob Herring
2018-10-22 10:22 ` Chen-Yu Tsai
2018-10-23 15:11 ` Rob Herring
2018-10-24 20:22 ` Chen-Yu Tsai
2018-09-27 11:48 ` [PATCH 10/12] drm/panel: Add Bananapi S070WV20-CT16 MIPI-DSI panel driver Jagan Teki
2018-09-28 4:32 ` Chen-Yu Tsai
2018-10-04 16:06 ` Jagan Teki
2018-09-27 11:48 ` [PATCH 11/12] arm64: dts: allwinner: a64: Add DSI pipeline Jagan Teki
2018-09-27 17:16 ` Maxime Ripard
2018-09-27 11:48 ` [PATCH 12/12] arm64: dts: allwinner: bananapi-m64: Bananapi S070WV20-CT16 DSI panel Jagan Teki
2018-09-27 17:17 ` Maxime Ripard
2018-10-04 16:03 ` Jagan Teki
2018-10-05 15:31 ` Maxime Ripard
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