linux-kernel - Re: [linux-sunxi] [PATCH v3 06/16] drm/sun4i: Release exclusive clock lock when disabling TCON

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Message-ID: <3764594.86uYqsI6mN@jernej-laptop>
Date:   Thu, 08 Mar 2018 23:57:40 +0100
From:   Jernej Škrabec <jernej.skrabec@...l.net>
To:     Ondřej Jirman <megi@....cz>
Cc:     maxime.ripard@...e-electrons.com, wens@...e.org, airlied@...ux.ie,
        robh+dt@...nel.org, mark.rutland@....com, mturquette@...libre.com,
        sboyd@...nel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: Re: [linux-sunxi] [PATCH v3 06/16] drm/sun4i: Release exclusive clock lock when disabling TCON

Hi,

Dne četrtek, 08. marec 2018 ob 23:47:17 CET je Ondřej Jirman napisal(a):
> Hi,
> 
> On Thu, Mar 01, 2018 at 10:34:32PM +0100, Jernej Skrabec wrote:
> > 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 <jernej.skrabec@...l.net>
> > ---
> > 
> >  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:
> 

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

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.

Best regards,
Jernej

> $ 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.
> 
> >  static void sun4i_tcon_lvds_set_status(struct sun4i_tcon *tcon,
> > 
> > --
> > 2.16.2
> > 
> > --
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