linux-kernel - Re: [PATCH V12 3/7] dma: add Qualcomm Technologies HIDMA management driver

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Message-ID: <569CAB07.8020200@arm.com>
Date:	Mon, 18 Jan 2016 09:06:15 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Sinan Kaya <okaya@...eaurora.org>,
	Mark Rutland <mark.rutland@....com>
Cc:	dmaengine@...r.kernel.org, timur@...eaurora.org,
	devicetree@...r.kernel.org, cov@...eaurora.org,
	vinod.koul@...el.com, jcm@...hat.com, agross@...eaurora.org,
	arnd@...db.de, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kvmarm@...ts.cs.columbia.edu, christoffer.dall@...aro.org,
	shankerd@...eaurora.org, Vikram Sethi <vikrams@...eaurora.org>
Subject: Re: [PATCH V12 3/7] dma: add Qualcomm Technologies HIDMA management
 driver

On 15/01/16 22:47, Sinan Kaya wrote:
> On 1/15/2016 12:32 PM, Marc Zyngier wrote:
>>>> Do you have a link to that? Seeing it would help to ease my concerns.
>>>>
>>>> The QEMU driver has not been posted yet. As far as I know, it just discovers the memory
>>>> resources on the platform object and creates mappings for the guest machine only. 
>>>>
>>>> Shanker Donthineni and Vikram Sethi will post the QEMU patch later.
>> Then may I suggest you both synchronize your submissions? I'd really
>> like to hear from the QEMU maintainers that they are satisfied with that
>> side of the story as well.
> 
> The HIDMA QEMU driver is also based on VFIO platform driver in QEMU. It is not a new concept
> or new framework. All tried and tested solutions. 
> 
> The driver below is already using this feature. HIDMA is no exception. 
> I have verified functionality of HIDMA linux driver with HIDMA QEMU driver already.

That you have tested what you propose is the minimum you can do.

> https://lxr.missinglinkelectronics.com/qemu/hw/arm/sysbus-fdt.c#L67
> https://lxr.missinglinkelectronics.com/qemu/hw/vfio/calxeda-xgmac.c#L18
> https://lxr.missinglinkelectronics.com/qemu/include/hw/vfio/vfio-calxeda-xgmac.h 

None of which warrants that what you're doing is the right thing. Since
nobody has seen your QEMU code, I'm not going to take any bet.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...