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From: Florian Fainelli <f.fainelli@gmail•com>
To: Christoph Hellwig <hch@lst•de>,
	Nicolas Saenz Julienne <nsaenzjulienne@suse•de>
Cc: mbrugger@suse•com, Scott Branden <sbranden@broadcom•com>,
	Ray Jui <rjui@broadcom•com>, Russell King <linux@armlinux•org.uk>,
	linux-kernel@vger•kernel.org, Eric Anholt <eric@anholt•net>,
	bcm-kernel-feedback-list@broadcom•com,
	Stefan Wahren <wahrenst@gmx•net>,
	linux-arm-kernel@lists•infradead.org,
	linux-rpi-kernel@lists•infradead.org
Subject: Re: [RFC] ARM: bcm2835: register dmabounce on devices hooked to main interconnect
Date: Sat, 27 Jul 2019 10:36:46 +0200	[thread overview]
Message-ID: <f15ef16e-8e5c-4e9b-1cb2-c6602b15a4ec@gmail.com> (raw)
In-Reply-To: <20190723163433.GA2234@lst.de>



On 7/23/2019 6:34 PM, Christoph Hellwig wrote:
>> +static int bcm2835_needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
> 
> Too long line..
> 
>> +void __init bcm2835_init_early(void)
>> +{
>> +	if(of_machine_is_compatible("brcm,bcm2711"))
> 
> Odd formatting.
> 
> Otherwise this looks good to me.

Is this really the right way to solve this problem? First this is ARM
32-bit specific, and second, should not we have a way to indicate via
device tree that all peripherals behind the "soc" simple-bus parent node
are limited to 32-bit of DMA masks, but the specific memory map of the
BCM283x/BCM2711 makes it that only the last 1GB (0xC000_0000 -
0xffff_ffff) (which dma-ranges conveys already) is suitable for DMA into
the VPU uncached alias?
-- 
Florian

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      reply	other threads:[~2019-07-27  8:38 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-23 16:19 [RFC] ARM: bcm2835: register dmabounce on devices hooked to main interconnect Nicolas Saenz Julienne
2019-07-23 16:34 ` Christoph Hellwig
2019-07-27  8:36   ` Florian Fainelli [this message]

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