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From: Marc Zyngier <maz@kernel.org>
To: Peter Geis <pgwipeout@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] ITS fails to allocate on rk3568/rk3566
Date: Tue, 13 Apr 2021 16:51:12 +0100	[thread overview]
Message-ID: <87tuoambdb.wl-maz@kernel.org> (raw)
In-Reply-To: <CAMdYzYrNa_wJa9mvBkhDrvdNaDugR9Y=LEnbcVHxjxJS0UFcMg@mail.gmail.com>

On Tue, 13 Apr 2021 16:03:51 +0100,
Peter Geis <pgwipeout@gmail.com> wrote:
> 
> On Tue, Apr 13, 2021 at 10:01 AM Marc Zyngier <maz@kernel.org> wrote:

[...]

> > What happens if you hack all the allocations to happen in the low 4GB
> > of the PA space?
> 
> It seems to work correctly.
> The downstream hacks used GFP_DMA32 which gets discarded by
> kmalloc_fix_flags on certain allocations.
> Switching to GFP_DMA seems to have satisfied it, but it feels wrong
> using this code.
> Need to check the corner cases to make sure I'm not missing something.

The problem is that GFP_DMA doesn't always mean the same thing.
Overall, we need to hear from Rockchip about the exact nature of the
problem, and then we *may* be able to work something out.

I'd also like to understand whether it is broken because you happen to
have pre-release silicon that will never make it into the wild, or if
this is the real thing that is going to ship on millions of devices.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Peter Geis <pgwipeout@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] ITS fails to allocate on rk3568/rk3566
Date: Tue, 13 Apr 2021 16:51:12 +0100	[thread overview]
Message-ID: <87tuoambdb.wl-maz@kernel.org> (raw)
In-Reply-To: <CAMdYzYrNa_wJa9mvBkhDrvdNaDugR9Y=LEnbcVHxjxJS0UFcMg@mail.gmail.com>

On Tue, 13 Apr 2021 16:03:51 +0100,
Peter Geis <pgwipeout@gmail.com> wrote:
> 
> On Tue, Apr 13, 2021 at 10:01 AM Marc Zyngier <maz@kernel.org> wrote:

[...]

> > What happens if you hack all the allocations to happen in the low 4GB
> > of the PA space?
> 
> It seems to work correctly.
> The downstream hacks used GFP_DMA32 which gets discarded by
> kmalloc_fix_flags on certain allocations.
> Switching to GFP_DMA seems to have satisfied it, but it feels wrong
> using this code.
> Need to check the corner cases to make sure I'm not missing something.

The problem is that GFP_DMA doesn't always mean the same thing.
Overall, we need to hear from Rockchip about the exact nature of the
problem, and then we *may* be able to work something out.

I'd also like to understand whether it is broken because you happen to
have pre-release silicon that will never make it into the wild, or if
this is the real thing that is going to ship on millions of devices.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip

  reply	other threads:[~2021-04-13 15:51 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-12 20:49 [RFC] ITS fails to allocate on rk3568/rk3566 Peter Geis
2021-04-12 20:49 ` Peter Geis
2021-04-13  9:23 ` Marc Zyngier
2021-04-13  9:23   ` Marc Zyngier
     [not found]   ` <CAMdYzYruPyiT89FrbJhuV=c36PyRwZ7sT45abnv8rTv85AKRow@mail.gmail.com>
     [not found]     ` <87y2dmmggt.wl-maz@kernel.org>
2021-04-13 15:03       ` Peter Geis
2021-04-13 15:03         ` Peter Geis
2021-04-13 15:51         ` Marc Zyngier [this message]
2021-04-13 15:51           ` Marc Zyngier
2021-04-14 11:41           ` Peter Geis
2021-04-14 11:41             ` Peter Geis
2021-04-14 12:42             ` Marc Zyngier
2021-04-14 12:42               ` Marc Zyngier
2021-04-15  7:24               ` Kever Yang
2021-04-15  7:24                 ` Kever Yang
2021-04-15  8:11                 ` Marc Zyngier
2021-04-15  8:11                   ` Marc Zyngier
2021-04-16  1:13                   ` Kever Yang
2021-04-16  1:13                     ` Kever Yang
2021-04-16 15:23                     ` Marc Zyngier
2021-04-16 15:23                       ` Marc Zyngier
2021-04-21  1:40                       ` Kever Yang
2021-04-21  1:40                         ` Kever Yang
2021-04-21 10:23                         ` Marc Zyngier
2021-04-21 10:23                           ` Marc Zyngier

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