On Fri, Jun 14, 2019 at 12:03:13PM +0530, Jagan Teki wrote: > On Thu, Jun 13, 2019 at 6:56 PM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > > On Wed, Jun 05, 2019 at 01:17:11PM +0530, Jagan Teki wrote: > > > On Tue, Jun 4, 2019 at 3:30 PM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > > > > > > On Wed, May 29, 2019 at 11:44:56PM +0530, Jagan Teki wrote: > > > > > On Wed, May 29, 2019 at 8:24 PM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > > > > > > > > > > On Fri, May 24, 2019 at 03:48:51PM +0530, Jagan Teki wrote: > > > > > > > On Fri, May 24, 2019 at 2:04 AM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > On Mon, May 20, 2019 at 02:33:08PM +0530, Jagan Teki wrote: > > > > > > > > > According to "DRM kernel-internal display mode structure" in > > > > > > > > > include/drm/drm_modes.h the current driver is trying to include > > > > > > > > > sync timings along with front porch value while checking and > > > > > > > > > computing drq set bits in non-burst mode. > > > > > > > > > > > > > > > > > > mode->hsync_end - mode->hdisplay => horizontal front porch + sync > > > > > > > > > > > > > > > > > > With adding additional sync timings, the dsi controller leads to > > > > > > > > > wrong drq set bits for "bananapi,s070wv20-ct16" panel 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 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 > > > > > > > > > > > > > > > > > > But according to Allwinner A33, A64 BSP code [1] [3] the TCON DRQ for > > > > > > > > > non-burst DSI mode can be computed based on "horizontal front porch" > > > > > > > > > value only (no sync timings included). > > > > > > > > > > > > > > > > > > Detailed evidence for drq set bits based on A33 BSP [1] [2] > > > > > > > > > > > > > > > > > > => panel->lcd_ht - panel->lcd_x - panel->lcd_hbp - 20 > > > > > > > > > => (tt->hor_front_porch + lcdp->panel_info.lcd_hbp + > > > > > > > > > lcdp->panel_info.lcd_x) - panel->lcd_x - panel->lcd_hbp - 20 > > > > > > > > > => tt->hor_front_porch - 20 > > > > > > > > > > > > > > > > The thing is, while your explanation on the DRM side is sound, > > > > > > > > Allwinner has been using the hbp field of their panel description to > > > > > > > > store what DRM calls the backporch and the sync period. > > > > > > > > > > > > > > Exactly, hbp = backporch + sync > > > > > > > https://github.com/BPI-SINOVOIP/BPI-M2M-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp/de/disp_lcd.c#L2046 > > > > > > > > > > > > > > And the above computation is rely on that as well. If you can see the > > > > > > > final out of the above computation you can get the front porch value > > > > > > > (w/o sync ) > > > > > > > > > > > > As I was saying, you are explaining it well for DRM, but in order for > > > > > > your last formula (the one coming from the BSP) to make sense, you > > > > > > have to explain that the horizontal back porch for Allwinner contains > > > > > > the sync period, otherwise your expansion of lcd_ht doesn't make > > > > > > sense. > > > > > > > > > > I'm not sure why we need to take care of back porch since the formula > > > > > clearly evaluating a result as front porch, without sync timing (as > > > > > current code included this sync), I keep the hbp and trying to > > > > > substitute the lcd_ht value so the end result would cancel hbp. > > > > > > > > Because it changes how lcd_ht expands. In the DRM case, it will expand > > > > to the displayed area, the front porch, the sync period and the back > > > > porch. > > > > > > > > In your case, you expand it to the displayed area, the front porch and > > > > the back porch, precisely because in Allwinner's case, the back porch > > > > has the sync period. > > > > > > I understand the point, but technically it matter about the final > > > computation result. May be we can even manage the same computation in > > > back porch, but I'm not sure. Since the final output doesn't involve > > > any sync length, why we can include that ie what I'm not sure. > > > > We have the following formula: > > lcd_ht - lcd_x - lcd_hbp - 20 > > > > Using the concepts as they are defined in DRM, this expands to: > > x + hbp + hsync + hfp - x - hbp - 20 > > Here is diff between allwinner hbp vs hbp in DRM. > > Say hbp in DRM can call it hbackporch, so > > => x + hbackporch + hsync + hfp - -x - hbp - 20 > > (and here we need to substitute hbp formula from allwinner since the > actual equation would coming from there > https://github.com/BPI-SINOVOIP/BPI-M2M-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp/de/disp_lcd.c#L2046) And this is precisely what needs to be said, with an explanation about where that hor_back_porch is being used later on, and what impact it could have. Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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