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From: Julien Grall <julien.grall@arm.com>
To: Rob Herring <robh@kernel.org>,
	Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: linux-kernel@vger.kernel.org, Robin Murphy <robin.murphy@arm.com>,
	Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
	Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	xen-devel@lists.xenproject.org
Subject: Re: [RFC PATCH] xen/gntdev: Stop abusing DT of_dma_configure API
Date: Thu, 26 Sep 2019 10:49:59 +0100	[thread overview]
Message-ID: <e898c025-32a7-1d2c-3501-c99556f7cdd4@arm.com> (raw)
In-Reply-To: <20190925215006.12056-1-robh@kernel.org>

Hi Rob,


On 9/25/19 10:50 PM, Rob Herring wrote:
> As the comment says, this isn't a DT based device. of_dma_configure()
> is going to stop allowing a NULL DT node, so this needs to be fixed.

And this can't work on arch not selecting CONFIG_OF and can select 
CONFIG_XEN_GRANT_DMA_ALLOC.

We are lucky enough on x86 because, AFAICT, arch_setup_dma_ops is just a 
nop.

> 
> Not sure exactly what setup besides arch_setup_dma_ops is needed...

We probably want to update dma_mask, coherent_dma_mask and dma_pfn_offset.

Also, while look at of_configure_dma, I noticed that we consider the DMA 
will not be coherent for the grant-table. Oleksandr, do you know why 
they can't be coherent?

Cheers,

-- 
Julien Grall

  parent reply	other threads:[~2019-09-26  9:50 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 21:50 Rob Herring
2019-09-26  9:06 ` Nicolas Saenz Julienne
2019-09-26  9:49 ` Julien Grall [this message]
2019-09-26 10:17   ` Oleksandr Andrushchenko
2019-09-26 10:46     ` Robin Murphy
2019-09-26 11:16       ` Oleksandr Andrushchenko
2019-09-26 19:27         ` Rob Herring
2019-10-01 18:23           ` Stefano Stabellini
2019-10-02  4:42             ` Oleksandr Andrushchenko

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