Re: [REGRESSION] drm/etnaviv: command buffer outside valid memory window - Russell King

From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [REGRESSION] drm/etnaviv: command buffer outside valid memory window
Date: Thu, 27 Jun 2019 17:48:18 +0100	[thread overview]
Message-ID: <20190627164818.5ybdvgjhxgq32jfe@shell.armlinux.org.uk> (raw)
In-Reply-To: <1561646970.2587.48.camel@pengutronix.de>

On Thu, Jun 27, 2019 at 04:49:30PM +0200, Lucas Stach wrote:
> Am Donnerstag, den 27.06.2019, 15:32 +0100 schrieb Russell King - ARM Linux admin:
> > On Thu, Jun 27, 2019 at 11:04:17AM +0100, Russell King - ARM Linux admin wrote:
> > > On Thu, Jun 27, 2019 at 11:20:15AM +0200, Lucas Stach wrote:
> > > > Am Samstag, den 22.06.2019, 17:16 +0100 schrieb Russell King - ARM Linux admin:
> > > > > While updating my various systems for the TCP SACK issue, I notice
> > > > > that while most platforms are happy, the Cubox-i4 is not.  During
> > > > > boot, we get:
> > > > > 
> > > > > [    0.000000] cma: Reserved 256 MiB at 0x30000000
> > > > > ...
> > > > > [    0.000000] Kernel command line: console=ttymxc0,115200n8 console=tty1 video=mxcfb0:dev=hdmi root=/dev/nfs rw cma=256M ahci_imx.hotplug=1 splash resume=/dev/sda1
> > > > > [    0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
> > > > > [    0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
> > > > > [    0.000000] Memory: 1790972K/2097152K available (8471K kernel code, 693K rwdata, 2844K rodata, 500K init, 8062K bss, 44036K reserved, 262144K cma-reserved, 1310720K highmem)
> > > > > ...
> > > > > [   13.101098] etnaviv-gpu 130000.gpu: command buffer outside valid memory window
> > > > > [   13.171963] etnaviv-gpu 134000.gpu: command buffer outside valid memory window
> > > > 
> > > > Yes, that's a regression due to different default CMA area placement
> > > > and etnaviv not being smart enough to move the linear window to the
> > > > right offset.
> > > 
> > > As it's a user visible regression, it needs fixing, either by reverting
> > > the changes that caused it or by some other issue.  In the kernel, the
> > > policy is "if a bug fix causes a regression, the bug fix was itself
> > > wrong".  We don't fix one person's bug if it causes a regression for
> > > someone else.
> > > 
> > > Please resolve the acknowledged regression.
> 
> The regression is caused due to a different CMA placement, which is
> outside of the control of etnaviv. If you can point to the commit
> causing this change in placement we could work with the
> authors/maintainers of this code to get rid of the regression.
> Currently I don't have the bandwidth to pinpoint the offending code
> change.

Ok, thanks for the explanation.

Well, the problem has become weirder.  I'm unable to reproduce the hang
now - the only change has been to add your patch for the unload issue,
as well as temporarily disabling lightdm's startup at boot (which is
now back as it was.)  Odd.

-- 
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