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Date:   Fri, 14 Jun 2019 16:28:10 +0200
From:   Maxime Ripard <maxime.ripard@bootlin.com>
To:     Jagan Teki <jagan@amarulasolutions.com>
Cc:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        Chen-Yu Tsai <wens@csie.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Bhushan Shah <bshah@mykolab.com>,
        Vasily Khoruzhick <anarsoul@gmail.com>,
        =?utf-8?B?5Z2a5a6a5YmN6KGM?= <powerpan@qq.com>,
        Michael Trimarchi <michael@amarulasolutions.com>,
        linux-amarula <linux-amarula@amarulasolutions.com>,
        linux-sunxi <linux-sunxi@googlegroups.com>
Subject: Re: [PATCH v10 02/11] drm/sun4i: dsi: Update start value in video
 start delay
Message-ID: <20190614142810.hbdaikbk7immwzc3@flea>
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On Thu, Jun 13, 2019 at 01:34:04PM +0530, Jagan Teki wrote:
> On Fri, May 31, 2019 at 12:23 AM Maxime Ripard
> <maxime.ripard@bootlin.com> wrote:
> >
> > On Fri, May 24, 2019 at 03:55:42PM +0530, Jagan Teki wrote:
> > > On Fri, May 24, 2019 at 2:07 AM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > > >
> > > > On Mon, May 20, 2019 at 02:33:09PM +0530, Jagan Teki wrote:
> > > > > start value in video start delay computation done in below commit
> > > > > is as per the legacy bsp drivers/video/sunxi/legacy..
> > > > > "drm/sun4i: dsi: Change the start delay calculation"
> > > > > (sha1: da676c6aa6413d59ab0a80c97bbc273025e640b2)
> > > > >
> > > > > This existing start delay computation gives start value of 35,
> > > > > for "bananapi,s070wv20-ct16" panel timings which indeed trigger
> > > > > panel flip_done timed out as:
> > > > >
> > > > >  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 Tainted: G        W         5.1.0-next-20190514-00025-gf928bc7cc146 #15
> > > > >  Hardware name: Allwinner sun8i Family
> > > > >  Workqueue: events deferred_probe_work_func
> > > > >  [<c010ed54>] (unwind_backtrace) from [<c010b76c>] (show_stack+0x10/0x14)
> > > > >  [<c010b76c>] (show_stack) from [<c0688c90>] (dump_stack+0x84/0x98)
> > > > >  [<c0688c90>] (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 [<c0411cb0>] (drm_fb_helper_pan_display+0xac/0x1d0)
> > > > >  [<c0411cb0>] (drm_fb_helper_pan_display) from [<c03a4e84>] (fb_pan_display+0xcc/0x134)
> > > > >  [<c03a4e84>] (fb_pan_display) from [<c03b1214>] (bit_update_start+0x14/0x30)
> > > > >  [<c03b1214>] (bit_update_start) from [<c03afe94>] (fbcon_switch+0x3d8/0x4e0)
> > > > >  [<c03afe94>] (fbcon_switch) from [<c03ec930>] (redraw_screen+0x174/0x238)
> > > > >  [<c03ec930>] (redraw_screen) from [<c03aceb4>] (fbcon_prepare_logo+0x3c4/0x400)
> > > > >  [<c03aceb4>] (fbcon_prepare_logo) from [<c03ad2b8>] (fbcon_init+0x3c8/0x5ac)
> > > > >  [<c03ad2b8>] (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 [<c044b5b0>] (try_to_bring_up_master+0x164/0x1a0)
> > > > >  [<c044b5b0>] (try_to_bring_up_master) from [<c044b680>] (__component_add+0x94/0x140)
> > > > >  [<c044b680>] (__component_add) from [<c0445e1c>] (sun6i_dsi_probe+0x144/0x234)
> > > > >  [<c0445e1c>] (sun6i_dsi_probe) from [<c0452f0c>] (platform_drv_probe+0x48/0x9c)
> > > > >  [<c0452f0c>] (platform_drv_probe) from [<c04512e4>] (really_probe+0x1dc/0x2c8)
> > > > >  [<c04512e4>] (really_probe) from [<c0451530>] (driver_probe_device+0x60/0x160)
> > > > >  [<c0451530>] (driver_probe_device) from [<c044f7bc>] (bus_for_each_drv+0x74/0xb8)
> > > > >  [<c044f7bc>] (bus_for_each_drv) from [<c0451094>] (__device_attach+0xd0/0x13c)
> > > > >  [<c0451094>] (__device_attach) from [<c045048c>] (bus_probe_device+0x84/0x8c)
> > > > >  [<c045048c>] (bus_probe_device) from [<c0450918>] (deferred_probe_work_func+0x64/0x90)
> > > > >  [<c0450918>] (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 755e10f62b83f396 ]---
> > > > >  Console: switching to colour frame buffer device 100x30
> > > > >  [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
> > > > >
> > > > > But the expected start delay value is 1 which is confirmed from
> > > > > new bsp [2].
> > > >
> > > > If you're saying that the "legacy" link (second one) is the new BSP.
> > >
> > > Will update, thanks.
> > >
> > > >
> > > > > The important and unclear note on legacy and new bsp codes [1] [2]
> > > > > is both use similar start computation initially but it later reassign
> > > > > it to 1 in new bsp.
> > > >
> > > > Then start_delay is never reassigned to 1 in that link, and is clamped
> > > > between 8 and 100 as the code that you are removing is doing.
> > >
> > > Please see the link one more please
> > > https://github.com/BPI-SINOVOIP/BPI-M2M-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp/de/lowlevel_sun8iw5/de_dsi.c#L807
> > >
> > > >
> > > > > Unfortunately we don't have any evidence or documentation for this
> > > > > reassignment to 1 in new bsp, but it is working with all supported
> > > > > panels in A33, A64.
> > > >
> > > > No, it's not. That was added to fix a panel that is supported today.
> > >
> > > No, I have see this in A33, A64. and these are controller drivers
> > > right, if it panel fix and it should be part of panel driver isn't
> > > it?
> >
> > I'm not sure to follow that argument. You're submitting that fix to
> > allow other panels to work, right? So surely, some issues that can be
> > found using a given panel might not be solely fixed in the panel driver.
>
> I'm not sure I understand this. I have been verifying different panels
> to check across. and this change literally in BSP and the BSP code is
> using this based on the logs confirmation. all the logs and working
> conditions shows that the fix would required in dsi.

You were saying that your fix was working with all supported panels in
A33, A64. That's simply not true, since at least one of mine will be
broken by this.

You can say that it fixes all the panels *you* have, but it's
certainly not all of them.

> > > We can even see the same in pin64 longsleep kernel and others.
> > >
> > > https://github.com/BPI-SINOVOIP/BPI-M2M-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp/de/lowlevel_sun8iw5/de_dsi.c#L807
> > > https://github.com/longsleep/linux-pine64/blob/pine64-hacks-1.2/drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c#L730
> >
> > Yeah, and both of these have the legacy driver part with the clamping
> > too.
>
> Yes, both legacy has clamping, but not using.

See the links above, they are being used.

> they used it in new version driver which I'm referring above.

I'm sorry, but I just don't get what you're saying. The links
mentionned above are clearly showing that it's being used, while the
other, !legacy, driver doesn't have them anymore. So it seems to be
exactly the opposite of what you're saying.

Maxime

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

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