linux-kernel - Re: [PATCH v4 0/3] mmc: sdhci: Set DMA mask properly

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Message-ID: <56E955A0.7010502@intel.com>
Date:	Wed, 16 Mar 2016 14:46:24 +0200
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Alexandre Courbot <acourbot@...dia.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Arnd Bergmann <arnd@...db.de>
Cc:	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	gnurou@...il.com
Subject: Re: [PATCH v4 0/3] mmc: sdhci: Set DMA mask properly

On 07/03/16 04:07, Alexandre Courbot wrote:
> 64-bit capable devices are supposed to set their own DMA mask. Currently
> this does not happen for sdhci devices excepted for the two (sdhci-acpi
> and sdhci-pci) that define a enable_dma() hook and do it there. However
> this hook is called from several places while DMA mask is supposed to
> be set only once ; for instance the sdhci-acpi driver maintains a flag
> just to make sure the DMA mask is set only upon the first call of this
> hook.
> 
> For the vast majority of drivers that do not define a enable_dma() hook, the
> default 32-bit DMA mask is used and there is a risk of using unneeded bounce
> buffers on hosts capable of 64-bit addressing.
> 
> The first patch adds a default DMA mask setting function that is called when
> a DMA-capable host is added. It tries to set sane DMA masks according to the
> device's reported capabilities.
> 
> The addition of this function seems to make the same code in sdhci-acpi and
> sdhci-pci redundant, so it is removed from these drivers. On top of making
> this series a negative line count, it also removes one usage of the obsolete
> pci_set_dma_mask() function.
> 
> Changes since v3:
> - Unset the SDHCI_USE_64_BIT_DMA flag if setting of 64-bit mask failed
> - Carry Acked-bys
> 
> Alexandre Courbot (3):
>   mmc: sdhci: Set DMA mask when adding host
>   mmc: sdhci-acpi: Remove enable_dma() hook
>   mmc: sdhci-pci: Do not set DMA mask in enable_dma()
> 
>  drivers/mmc/host/sdhci-acpi.c     | 30 ------------------------
>  drivers/mmc/host/sdhci-pci-core.c | 15 ------------
>  drivers/mmc/host/sdhci.c          | 48 +++++++++++++++++++++++++++++++++------
>  3 files changed, 41 insertions(+), 52 deletions(-)
> 

I had a couple of questions which have been answered, so for all 3 patches:

Acked-by: Adrian Hunter <adrian.hunter@...el.com>