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Teki Subject: Re: [PATCH v10 04/11] drm/sun4i: tcon: Compute DCLK dividers based on format, lanes Message-ID: <20190523204823.mx7l4ozklzdh7npn@flea> References: <20190520090318.27570-1-jagan@amarulasolutions.com> <20190520090318.27570-5-jagan@amarulasolutions.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190520090318.27570-5-jagan@amarulasolutions.com> User-Agent: NeoMutt/20180716 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190523_134843_745216_3ADF1D7F X-CRM114-Status: GOOD ( 13.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bshah@mykolab.com, David Airlie , linux-sunxi@googlegroups.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, powerpan@qq.com, Chen-Yu Tsai , Daniel Vetter , michael@amarulasolutions.com, linux-amarula@amarulasolutions.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 20, 2019 at 02:33:11PM +0530, Jagan Teki wrote: > pll-video => pll-mipi => tcon0 => tcon0-pixel-clock is the typical > MIPI clock topology in Allwinner DSI controller. > > TCON dotclock driver is computing the desired DCLK divider based on > panel pixel clock along with input DCLK min, max divider values from > tcon driver and that would eventually set the pll-mipi clock rate. > > The current code is passing dsi min and max divider value as 4 via > tcon driver which would ended-up triggering below vblank wait timed out > warning on "bananapi,s070wv20-ct16" panel. > > 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-20190514-00025-g5186cdf10757-dirty #6 > Hardware name: Allwinner sun8i Family > Workqueue: events deferred_probe_work_func > [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [] (show_stack) from [] (dump_stack+0x84/0x98) > [] (dump_stack) from [] (__warn+0xfc/0x114) > [] (__warn) from [] (warn_slowpath_fmt+0x44/0x68) > [] (warn_slowpath_fmt) from [] (drm_atomic_helper_wait_for_vblanks.part.1+0x298/0x2a0) > [] (drm_atomic_helper_wait_for_vblanks.part.1) from [] (drm_atomic_helper_commit_tail_rpm+0x5c/0x6c) > [] (drm_atomic_helper_commit_tail_rpm) from [] (commit_tail+0x40/0x6c) > [] (commit_tail) from [] (drm_atomic_helper_commit+0xbc/0x128) > [] (drm_atomic_helper_commit) from [] (restore_fbdev_mode_atomic+0x1cc/0x1dc) > [] (restore_fbdev_mode_atomic) from [] (drm_fb_helper_restore_fbdev_mode_unlocked+0x54/0xa0) > [] (drm_fb_helper_restore_fbdev_mode_unlocked) from [] (drm_fb_helper_set_par+0x30/0x54) > [] (drm_fb_helper_set_par) from [] (fbcon_init+0x560/0x5ac) > [] (fbcon_init) from [] (visual_init+0xbc/0x104) > [] (visual_init) from [] (do_bind_con_driver+0x1b0/0x390) > [] (do_bind_con_driver) from [] (do_take_over_console+0x13c/0x1c4) > [] (do_take_over_console) from [] (do_fbcon_takeover+0x74/0xcc) > [] (do_fbcon_takeover) from [] (notifier_call_chain+0x44/0x84) > [] (notifier_call_chain) from [] (__blocking_notifier_call_chain+0x48/0x60) > [] (__blocking_notifier_call_chain) from [] (blocking_notifier_call_chain+0x18/0x20) > [] (blocking_notifier_call_chain) from [] (register_framebuffer+0x1e0/0x2f8) > [] (register_framebuffer) from [] (__drm_fb_helper_initial_config_and_unlock+0x2fc/0x50c) > [] (__drm_fb_helper_initial_config_and_unlock) from [] (drm_fbdev_client_hotplug+0xe8/0x1b8) > [] (drm_fbdev_client_hotplug) from [] (drm_fbdev_generic_setup+0x88/0x118) > [] (drm_fbdev_generic_setup) from [] (sun4i_drv_bind+0x128/0x160) > [] (sun4i_drv_bind) from [] (try_to_bring_up_master+0x164/0x1a0) > [] (try_to_bring_up_master) from [] (__component_add+0x94/0x140) > [] (__component_add) from [] (sun6i_dsi_probe+0x144/0x234) > [] (sun6i_dsi_probe) from [] (platform_drv_probe+0x48/0x9c) > [] (platform_drv_probe) from [] (really_probe+0x1dc/0x2c8) > [] (really_probe) from [] (driver_probe_device+0x60/0x160) > [] (driver_probe_device) from [] (bus_for_each_drv+0x74/0xb8) > [] (bus_for_each_drv) from [] (__device_attach+0xd0/0x13c) > [] (__device_attach) from [] (bus_probe_device+0x84/0x8c) > [] (bus_probe_device) from [] (deferred_probe_work_func+0x64/0x90) > [] (deferred_probe_work_func) from [] (process_one_work+0x204/0x420) > [] (process_one_work) from [] (worker_thread+0x274/0x5a0) > [] (worker_thread) from [] (kthread+0x11c/0x14c) > [] (kthread) from [] (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 4017fea4906ab391 ]--- > > But accordingly to Allwinner A33, A64 BSP codes [1] [2] this divider > is clearly using 'format/lanes' for dsi divider value, dsi_clk.clk_div > > Which would compute the pll_freq and set a clock rate for it in > [3] and [4] respectively. > > The same issue has reproduced in A33, A64 with 4-lane and 2-lane devices > and got fixed with this computation logic 'format/lanes', so this patch > using dclk min and max dividers as per BSP. > > [1] https://github.com/BPI-SINOVOIP/BPI-M2M-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp/de/disp_lcd.c#L1106 > [2] https://github.com/BPI-SINOVOIP/BPI-M64-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/disp_al.c#L213 > [3] https://github.com/BPI-SINOVOIP/BPI-M2M-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp/de/disp_lcd.c#L1127 > [4] https://github.com/BPI-SINOVOIP/BPI-M2M-bsp/blob/master/linux-sunxi/drivers/video/sunxi/disp/de/disp_lcd.c#L1161 In that mail, I've pointed out that clk_div isn't used for the TCON dclk divider: http://lists.infradead.org/pipermail/linux-arm-kernel/2019-February/629596.html The only reply you've sent is that you indeed see that the divider is set to 4 in the BSP, but you're now saying that the BSP can change it. If so, then please point exactly the flaw in the explanation in that mail. Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel