Date:   Mon, 20 May 2019 14:33:11 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Chen-Yu Tsai <wens@...e.org>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     bshah@...olab.com, Vasily Khoruzhick <anarsoul@...il.com>,
        powerpan@...com, michael@...rulasolutions.com,
        linux-amarula@...rulasolutions.com, linux-sunxi@...glegroups.com,
        Jagan Teki <jagan@...rulasolutions.com>
Subject: [PATCH v10 04/11] drm/sun4i: tcon: Compute DCLK dividers based on format, lanes

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
 [<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 [<c044b588>] (try_to_bring_up_master+0x164/0x1a0)
 [<c044b588>] (try_to_bring_up_master) from [<c044b658>] (__component_add+0x94/0x140)
 [<c044b658>] (__component_add) from [<c0445e0c>] (sun6i_dsi_probe+0x144/0x234)
 [<c0445e0c>] (sun6i_dsi_probe) from [<c0452ee4>] (platform_drv_probe+0x48/0x9c)
 [<c0452ee4>] (platform_drv_probe) from [<c04512bc>] (really_probe+0x1dc/0x2c8)
 [<c04512bc>] (really_probe) from [<c0451508>] (driver_probe_device+0x60/0x160)
 [<c0451508>] (driver_probe_device) from [<c044f794>] (bus_for_each_drv+0x74/0xb8)
 [<c044f794>] (bus_for_each_drv) from [<c045106c>] (__device_attach+0xd0/0x13c)
 [<c045106c>] (__device_attach) from [<c0450464>] (bus_probe_device+0x84/0x8c)
 [<c0450464>] (bus_probe_device) from [<c04508f0>] (deferred_probe_work_func+0x64/0x90)
 [<c04508f0>] (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 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

Tested-by: Merlijn Wajer <merlijn@...zup.org>
Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 9d8d8124b1f6..8f93121fead4 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -341,8 +341,8 @@ static void sun4i_tcon0_mode_set_cpu(struct sun4i_tcon *tcon,
 	u32 block_space, start_delay;
 	u32 tcon_div;
 
-	tcon->dclk_min_div = SUN6I_DSI_TCON_DIV;
-	tcon->dclk_max_div = SUN6I_DSI_TCON_DIV;
+	tcon->dclk_min_div = bpp/lanes;
+	tcon->dclk_max_div = bpp/lanes;
 
 	sun4i_tcon0_mode_set_common(tcon, mode);
 
-- 
2.18.0.321.gffc6fa0e3

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