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Date:   Thu, 03 Oct 2019 14:51:42 +0800
In-Reply-To: <20191003064527.15128-2-jagan@amarulasolutions.com>
References: <20191003064527.15128-1-jagan@amarulasolutions.com> <20191003064527.15128-2-jagan@amarulasolutions.com>
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Subject: Re: [PATCH v11 1/7] drm/sun4i: dsi: Fix TCON DRQ set bits
To:     Jagan Teki <jagan@amarulasolutions.com>,
        Maxime Ripard <mripard@kernel.org>,
        Chen-Yu Tsai <wens@csie.org>, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>
CC:     michael@amarulasolutions.com,
        linux-sunxi <linux-sunxi@googlegroups.com>,
        dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org
From:   Icenowy Zheng <icenowy@aosc.io>
Message-ID: <DB2FB6E5-E4B5-40F4-A05F-9A2303FCA1AE@aosc.io>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


于 2019年10月3日 GMT+08:00 下午2:45:21, Jagan Teki <jagan@amarulasolutions.com> 写到:
>The LCD timing definitions between Linux DRM vs Allwinner are
>different,
>below diagram shows this clear differences.
>
>           Active                 Front           Sync           Back
>           Region                 Porch                          Porch
><-----------------------><----------------><--------------><-------------->
>  //////////////////////|
> ////////////////////// |
>//////////////////////  |..................               
>................
>                                           ________________
><----- [hv]display ----->
><------------- [hv]sync_start ------------>
><--------------------- [hv]sync_end ---------------------->
><-------------------------------- [hv]total
>------------------------------>
>
><----- lcd_[xy] -------->		  <- lcd_[hv]spw ->
>					  <---------- lcd_[hv]bp --------->
><-------------------------------- lcd_[hv]t
>------------------------------>
>
>The DSI driver misinterpreted the hbp term from the BSP code to refer
>only to the backporch, when in fact it was backporch + sync. Thus the
>driver incorrectly used the horizontal front porch plus sync in its
>calculation of the DRQ set bit value, when it should not have included
>the sync timing.
>
>Including additional sync timings leads to flip_done timed out as:

I don't think attaching this error infomation is useful at all.

It's just timing mismatch.

>
>WARNING: CPU: 0 PID: 31 at drivers/gpu/drm/drm_atomic_helper.c:1429
>drm_atomic_helper_wait_for_vblanks.part.1+0x298/0x2a0
>[CRTC:46:crtc-0] vblank wait timed out
>Modules linked in:
>CPU: 0 PID: 31 Comm: kworker/0:1 Not tainted
>5.1.0-next-20190514-00026-g01f0c75b902d-dirty #13
>Hardware name: Allwinner sun8i Family
>Workqueue: events deferred_probe_work_func
>[<c010ed54>] (unwind_backtrace) from [<c010b76c>]
>(show_stack+0x10/0x14)
>[<c010b76c>] (show_stack) from [<c0688c70>] (dump_stack+0x84/0x98)
>[<c0688c70>] (dump_stack) from [<c011d9e4>] (__warn+0xfc/0x114)
>[<c011d9e4>] (__warn) from [<c011da40>] (warn_slowpath_fmt+0x44/0x68)
>[<c011da40>] (warn_slowpath_fmt) from [<c040cd50>]
>(drm_atomic_helper_wait_for_vblanks.part.1+0x298/0x2a0)
>[<c040cd50>] (drm_atomic_helper_wait_for_vblanks.part.1) from
>[<c040e694>] (drm_atomic_helper_commit_tail_rpm+0x5c/0x6c)
>[<c040e694>] (drm_atomic_helper_commit_tail_rpm) from [<c040e4dc>]
>(commit_tail+0x40/0x6c)
>[<c040e4dc>] (commit_tail) from [<c040e5cc>]
>(drm_atomic_helper_commit+0xbc/0x128)
>[<c040e5cc>] (drm_atomic_helper_commit) from [<c0411b64>]
>(restore_fbdev_mode_atomic+0x1cc/0x1dc)
>[<c0411b64>] (restore_fbdev_mode_atomic) from [<c04156f8>]
>(drm_fb_helper_restore_fbdev_mode_unlocked+0x54/0xa0)
>[<c04156f8>] (drm_fb_helper_restore_fbdev_mode_unlocked) from
>[<c0415774>] (drm_fb_helper_set_par+0x30/0x54)
>[<c0415774>] (drm_fb_helper_set_par) from [<c03ad450>]
>(fbcon_init+0x560/0x5ac)
>[<c03ad450>] (fbcon_init) from [<c03eb8a0>] (visual_init+0xbc/0x104)
>[<c03eb8a0>] (visual_init) from [<c03ed1b8>]
>(do_bind_con_driver+0x1b0/0x390)
>[<c03ed1b8>] (do_bind_con_driver) from [<c03ed780>]
>(do_take_over_console+0x13c/0x1c4)
>[<c03ed780>] (do_take_over_console) from [<c03ad800>]
>(do_fbcon_takeover+0x74/0xcc)
>[<c03ad800>] (do_fbcon_takeover) from [<c013c9c8>]
>(notifier_call_chain+0x44/0x84)
>[<c013c9c8>] (notifier_call_chain) from [<c013cd20>]
>(__blocking_notifier_call_chain+0x48/0x60)
>[<c013cd20>] (__blocking_notifier_call_chain) from [<c013cd50>]
>(blocking_notifier_call_chain+0x18/0x20)
>[<c013cd50>] (blocking_notifier_call_chain) from [<c03a6e44>]
>(register_framebuffer+0x1e0/0x2f8)
>[<c03a6e44>] (register_framebuffer) from [<c04153c0>]
>(__drm_fb_helper_initial_config_and_unlock+0x2fc/0x50c)
>[<c04153c0>] (__drm_fb_helper_initial_config_and_unlock) from
>[<c04158c8>] (drm_fbdev_client_hotplug+0xe8/0x1b8)
>[<c04158c8>] (drm_fbdev_client_hotplug) from [<c0415a20>]
>(drm_fbdev_generic_setup+0x88/0x118)
>[<c0415a20>] (drm_fbdev_generic_setup) from [<c043f060>]
>(sun4i_drv_bind+0x128/0x160)
>[<c043f060>] (sun4i_drv_bind) from [<c044b598>]
>(try_to_bring_up_master+0x164/0x1a0)
>[<c044b598>] (try_to_bring_up_master) from [<c044b668>]
>(__component_add+0x94/0x140)
>[<c044b668>] (__component_add) from [<c0445e1c>]
>(sun6i_dsi_probe+0x144/0x234)
>[<c0445e1c>] (sun6i_dsi_probe) from [<c0452ef4>]
>(platform_drv_probe+0x48/0x9c)
>[<c0452ef4>] (platform_drv_probe) from [<c04512cc>]
>(really_probe+0x1dc/0x2c8)
>[<c04512cc>] (really_probe) from [<c0451518>]
>(driver_probe_device+0x60/0x160)
>[<c0451518>] (driver_probe_device) from [<c044f7a4>]
>(bus_for_each_drv+0x74/0xb8)
>[<c044f7a4>] (bus_for_each_drv) from [<c045107c>]
>(__device_attach+0xd0/0x13c)
>[<c045107c>] (__device_attach) from [<c0450474>]
>(bus_probe_device+0x84/0x8c)
>[<c0450474>] (bus_probe_device) from [<c0450900>]
>(deferred_probe_work_func+0x64/0x90)
>[<c0450900>] (deferred_probe_work_func) from [<c0135970>]
>(process_one_work+0x204/0x420)
>[<c0135970>] (process_one_work) from [<c013690c>]
>(worker_thread+0x274/0x5a0)
>[<c013690c>] (worker_thread) from [<c013b3d8>] (kthread+0x11c/0x14c)
>[<c013b3d8>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
>Exception stack(0xde539fb0 to 0xde539ff8)
>9fa0:                                     00000000 00000000 00000000
>00000000
>9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000
>00000000
>9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
>---[ end trace b57eb1e5c64c6b8b ]---
>random: fast init done
>[drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [CRTC:46:crtc-0]
>flip_done timed out
>[drm:drm_atomic_helper_wait_for_dependencies] *ERROR*
>[CONNECTOR:48:DSI-1] flip_done timed out
>[drm:drm_atomic_helper_wait_for_dependencies] *ERROR*
>[PLANE:30:plane-0] flip_done timed out
>
>With the terms(as described in above diagram) fixed, the panel
>displays correctly without any timeouts.
>
>Tested-by: Merlijn Wajer <merlijn@wizzup.org>
>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 1636344ba9ec..f83522717488 100644
>--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
>+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
>@@ -437,9 +437,9 @@ static void sun6i_dsi_setup_burst(struct sun6i_dsi
>*dsi,
> 			     SUN6I_DSI_BURST_LINE_SYNC_POINT(SUN6I_DSI_SYNC_POINT));
> 
> 		val = SUN6I_DSI_TCON_DRQ_ENABLE_MODE;
>-	} else if ((mode->hsync_end - mode->hdisplay) > 20) {
>+	} else if ((mode->hsync_start - mode->hdisplay) > 20) {
> 		/* Maaaaaagic */
>-		u16 drq = (mode->hsync_end - mode->hdisplay) - 20;
>+		u16 drq = (mode->hsync_start - mode->hdisplay) - 20;
> 
> 		drq *= mipi_dsi_pixel_format_to_bpp(device->format);
> 		drq /= 32;

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