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 07/12] drm/sun4i: sun6i_mipi_dsi: Fix TCON DRQ set bits
Date: Thu, 27 Sep 2018 18:58:53 +0200 [thread overview]
Message-ID: <20180927165853.dpluekbqzat663q7@flea> (raw)
In-Reply-To: <20180927114850.24565-8-jagan@amarulasolutions.com>
On Thu, Sep 27, 2018 at 05:18:45PM +0530, Jagan Teki wrote:
> TCON DRQ set bits for non-burst DSI mode can computed via
> horizontal front porch instead of front porch + sync timings.
>
> Since there no documentation for TCON_DRQ_REG(0x7c) register
> this change is taken as reference from BPI-M64-bsp.
Detailing more what the issue is would be great.
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> index 599284971ab6..9918fdb990ff 100644
> --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> @@ -367,9 +367,9 @@ static void sun6i_dsi_setup_burst(struct sun6i_dsi *dsi,
> struct mipi_dsi_device *device = dsi->device;
> u32 val = 0;
The computation here is in the A64 driver:
if ((panel->lcd_ht - panel->lcd_x - panel->lcd_hbp) < 21) {
dsi_dev[sel]->dsi_tcon_drq.bits.drq_mode = 0;
} else {
dsi_dev[sel]->dsi_tcon_drq.bits.drq_set =
(panel->lcd_ht-panel->lcd_x-panel->lcd_hbp-20) *
dsi_pixel_bits[panel->lcd_dsi_format]/(8*4);
}
It is testing that the sync + front porch is smaller than 21, and
otherwise sets the drq.
> - if ((mode->hsync_end - mode->hdisplay) > 20) {
My code here is testing that the difference between hsync_end and
hdisplay is superior to 20, and sets the DRQ if true. The condition is
reversed, but otherwise, that difference is the front porch plus the
sync length.
> + if ((mode->hsync_start - mode->hdisplay) > 20) {
However, you are testing for just the front porch, unlike what your
commit log is saying, and unlike what allwinner's code is saying. So
this deserves some explanation.
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2018-09-27 16:58 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 [this message]
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
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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