Hi,

On Fri, Mar 09, 2018 at 07:19:33AM +0100, Jernej Škrabec wrote:

Hi,

Dne petek, 09. marec 2018 ob 01:44:55 CET je Ondřej Jirman napisal(a):

quoted

Hi,

I've debugged this further and it seems that the code has incorrect
assumptions. See docs for mode_set_nofb.

https://elixir.bootlin.com/linux/v4.16-rc4/source/include/drm/drm_modeset_he
lper_vtables.h#L209

Does this happen with https://github.com/jernejsk/linux-1/tree/h3_hdmi_v3 ?

Haven't tested, but it probably does, looking at the code. Try
restarting the X server a bunch of times.

I also tested running X, but I don't remember having the issue.
 

quoted

I've added traces to a few functions that call clk_.*exclusive.*()
functions, and I see this after a few restarts of Xorg server:

[    0.783842] *** sun4i_tcon1_mode_set()
[    0.783886] *** sun4i_tcon_channel_set_status(..., 1, true)
[    6.881690] *** sun4i_tcon_channel_set_status(..., 1, false)
[    6.881758] *** sun4i_tcon_channel_set_status(..., 1, true)
[   52.335085] *** sun4i_tcon_channel_set_status(..., 1, false)
[   52.335343] *** sun4i_tcon_channel_set_status(..., 1, true)
[   68.921079] *** sun4i_tcon_channel_set_status(..., 1, false)
[   68.921337] *** sun4i_tcon_channel_set_status(..., 1, true)

mode_set_nofb is called just once, yet sun4i_tcon_channel_set_status(..., 1,
false) is called multiple times, which leads to unbalanced calls to
clk_set_rate_exclusive and clk_rate_exclusive_put.

I don't know how to fix this.

Since there is no function to check if clock is protected, flag can be 
introduced within TCON which is set when clock rate is protected and unset 
when it is unprotected. That way we could track if clk_rate_exclusive_put() 
needs to be called or not.

I think that will not help. Protection is set in sun4i_tcon1_mode_set()
and that's called only once, but sun4i_tcon_channel_set_status(..., 1, false)
can be called multiple times, so the first call would disable protection
and the clock would be unprotected from then on, even though the display
would be active.

Perhaps the protection needs to be enabled in sun4i_tcon_channel_set_status(...,
true).

regards,
  o.

Best regards,
Jernej

quoted

regards,
  o.

On Fri, Mar 09, 2018 at 01:13:14AM +0100, 'Ondřej Jirman' via linux-sunxi 

wrote:

quoted

quoted

Hi Jernej,

On Thu, Mar 08, 2018 at 11:57:40PM +0100, Jernej Škrabec wrote:

quoted

Hi,

Dne četrtek, 08. marec 2018 ob 23:47:17 CET je Ondřej Jirman napisal(a):

quoted

Hi,

On Thu, Mar 01, 2018 at 10:34:32PM +0100, Jernej Skrabec wrote:

quoted

Currently exclusive TCON clock lock is never released, which, for
example, prevents changing resolution on HDMI.

In order to fix that, release clock when disabling TCON. TCON is
always
disabled first before new mode is set.

Signed-off-by: Jernej Skrabec <redacted>
---

 drivers/gpu/drm/sun4i/sun4i_tcon.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c

b/drivers/gpu/drm/sun4i/sun4i_tcon.c index
1d714c06ec9d..7f6c4125c89f
100644

--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -102,10 +102,12 @@ static void

sun4i_tcon_channel_set_status(struct
sun4i_tcon *tcon, int channel,>

 		return;
 	
 	}

-	if (enabled)
+	if (enabled) {

 		clk_prepare_enable(clk);

-	else
+	} else {
+		clk_rate_exclusive_put(clk);

 		clk_disable_unprepare(clk);

+	}

 }

At least in the linux-next/master I can't see clk_rate_exclusive_get 

call:

quoted

quoted

quoted

It is in drm-misc/drm-misc-fixes:
https://cgit.freedesktop.org/drm/drm-misc/commit/?h=drm-misc-fixes&id=79
d103a565d16b1893d990b2ee5e0fe71767759f

My patch is also applied in same branch, so there should be no issues
while
merging all those branches.

linux-next doesn't have either patches currently:
https://git.kernel.org/pub/
scm/linux/kernel/git/next/linux-next.git/log/drivers/gpu/drm/sun4i

This is issue only if you manually apply one patch without the other.

I have (and had) both patches applied. There's perhaps some code path,
where sun4i_tcon_channel_set_status(..., false) is called in unbalanced
way with regards to clk_set_rate_exclusive().

The issue occurs when starting Xorg. But Xorg works fine.

regards,

  o.
  

quoted

Best regards,
Jernej

quoted

$ git grep 'exclusive' linux-next/master -- drivers/gpu/drm/sun4i

linux-next/master:sun4i_hdmi.h:    * On sun5i the threshold is
exclusive,
i.e. does not include, linux-next/master:sun4i_tcon.c:
clk_rate_exclusive_put(clk); linux-next/master:sun4i_tcon.c:
clk_set_rate_exclusive(tcon->dclk, mode->crtc_clock * 1000);
linux-next/master:sun4i_tcon.c:   clk_set_rate_exclusive(tcon->sclk1,
mode->crtc_clock * 1000);

and the kernel complains too:

[  841.915161] ------------[ cut here ]------------
[  841.915187] WARNING: CPU: 0 PID: 273 at
/workspace/megous.com/orangepi-pc/linux-4.16/drivers/clk/clk.c:608
clk_rate_exclusive_put+0x48/0x4c [  841.915194] CPU: 0 PID: 273 Comm:
Xorg
Not tainted 4.16.0-rc4-00268-gbac2ecf73ed0 #13 [  841.915196] Hardware
name: Allwinner sun8i Family
[  841.915217] [<c0228440>] (unwind_backtrace) from [<c0225b90>]
(show_stack+0x10/0x14) [  841.915228] [<c0225b90>] (show_stack) from
[<c0b094bc>] (dump_stack+0x88/0x9c) [  841.915237] [<c0b094bc>]
(dump_stack) from [<c0240294>] (__warn+0xd4/0xf0) [  841.915244]
[<c0240294>] (__warn) from [<c0240380>] (warn_slowpath_null+0x40/0x48)
[
841.915250] [<c0240380>] (warn_slowpath_null) from [<c0619b6c>]
(clk_rate_exclusive_put+0x48/0x4c) [  841.915261] [<c0619b6c>]
(clk_rate_exclusive_put) from [<c0694624>]
(sun4i_tcon_set_status+0x178/0x2f0) [  841.915269] [<c0694624>]
(sun4i_tcon_set_status) from [<c06930c0>]
(sun4i_crtc_atomic_disable+0x7c/0xe4) [  841.915279] [<c06930c0>]
(sun4i_crtc_atomic_disable) from [<c06637fc>]
(drm_atomic_helper_commit_modeset_disables+0x390/0x46c) [  841.915288]
[<c06637fc>] (drm_atomic_helper_commit_modeset_disables) from
[<c0664df4>]
(drm_atomic_helper_commit_tail_rpm+0x18/0x64) [  841.915295]
[<c0664df4>]
(drm_atomic_helper_commit_tail_rpm) from [<c0664da8>]
(commit_tail+0x40/0x6c) [  841.915302] [<c0664da8>] (commit_tail) from
[<c06652b0>] (drm_atomic_helper_commit+0xbc/0x128) [  841.915311]
[<c06652b0>] (drm_atomic_helper_commit) from [<c0668d40>]
(restore_fbdev_mode_atomic+0x100/0x1fc) [  841.915319] [<c0668d40>]
(restore_fbdev_mode_atomic) from [<c0668f1c>]
(drm_fb_helper_dpms+0x50/0x130) [  841.915328] [<c0668f1c>]
(drm_fb_helper_dpms) from [<c0669e9c>] (drm_fb_helper_blank+0x54/0x90)
[
841.915337] [<c0669e9c>] (drm_fb_helper_blank) from [<c06088cc>]
(fb_blank+0x54/0xa8) [  841.915343] [<c06088cc>] (fb_blank) from
[<c0608c80>] (do_fb_ioctl+0x360/0x62c) [  841.915351] [<c0608c80>]
(do_fb_ioctl) from [<c0362648>] (do_vfs_ioctl+0x9c/0x774) [ 
841.915358]
[<c0362648>] (do_vfs_ioctl) from [<c0362d54>] (SyS_ioctl+0x34/0x58) [
841.915364] [<c0362d54>] (SyS_ioctl) from [<c0201120>]
(ret_fast_syscall+0x0/0x4c) [  841.915368] Exception stack(0xe5fc5fa8
to
0xe5fc5ff0)
[  841.915373] 5fa0:                   00674f10 00675460 0000000b
00004611
00000001 00000000 [  841.915379] 5fc0: 00674f10 00675460 00000001
00000036
00650474 00000000 006504a4 00675df8 [  841.915382] 5fe0: b61a502c
be8acb2c
b6192c38 b6b152ec
[  841.915386] ---[ end trace fa81b956197707f8 ]---

It looks like clk_rate_exclusive_put inside
sun4i_tcon_channel_set_status is called without first calling some
function that would call
clk_set_rate_exclusive, leading to unbalanced get/put calls.

regards,

  o.
  

quoted

 static void sun4i_tcon_lvds_set_status(struct sun4i_tcon *tcon,

--
2.16.2

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