Hi Sergei,

On Tuesday 29 October 2013 16:12:49 Sergei Shtylyov wrote:

On 29-10-2013 13:52, Laurent Pinchart wrote:

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Renesas ARM platforms are transitioning from single-platform to
multi-platform kernels using the new ARCH_SHMOBILE_MULTI. Make the
driver available on all ARM platforms to enable it on both ARCH_SHMOBILE
and ARCH_SHMOBILE_MULTI and increase build testing coverage.

Cc: Chris Ball <redacted>
Cc: Guennadi Liakhovetski <redacted>
Cc: Ian Molton <redacted>
Cc: linux-mmc at vger.kernel.org
Signed-off-by: Laurent Pinchart
[off-list ref]

[...]

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diff --git a/drivers/mmc/host/tmio_mmc_dma.c

b/drivers/mmc/host/tmio_mmc_dma.c index 65edb4a..535bc35 100644

--- a/drivers/mmc/host/tmio_mmc_dma.c
+++ b/drivers/mmc/host/tmio_mmc_dma.c

@@ -28,7 +28,7 @@ void tmio_mmc_enable_dma(struct tmio_mmc_host *host,

bool enable)>

  	if (!host->chan_tx || !host->chan_rx)
  	
  		return;

-#if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
+#if defined(CONFIG_SUPERH) || defined(CONFIG_ARM)

I'm not sure about this one. In principle DMA so far is only used on SDHI
with TMIO. But this #if was for a theoretical case, when a TMIO MMC IP
inside an MFD is also used with DMA. Bus since I had no indormation about
whether the CTL_DMA_ENABLE register was SDHI specific or not, I put it
under an #if for the time being. In any case, I don't think making it
#ifdef CONFIG_ARM makes much sense. We can either remove the #if
completely, or keep it to limit the scope of this write to sh-mobile
arches.

SUPERH || ARCH_SHMOBILE covers all the platforms this driver currently
builds on. Now that we're adding ARCH_SHMOBILE_MULTI the #if needs to
cover that case as well. I'm fine with limiting the CTL_DMA_ENABLE write
to SUPERH only (which would modify the driver's behaviour)

I'm afraid that would break the driver's ability to work in DMA mode on SH-
Mobile SoCs.

So can you confirm that writing the CTL_DMA_ENABLE register is required on all 
Renesas ARM SoCs (including SH-Mobile, R-Mobile and R-Car) ?

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or enabling it unconditionally, but I don't think adding a
defined(CONFIG_ARCH_SHMOBILE_MULTI) to the above #if makes sense, unless
there's a plan to add support for DMA for non-SH (including both SUPERH
and ARCH_SHMOBILE) platforms.

Not only the plan -- I have already posted the patches to do it for R8A777x,
and Simon has queued them for 3.13.

Could you please point me to those patches ?

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  	/* Switch DMA mode on or off - SuperH specific? */
  	sd_ctrl_write16(host, CTL_DMA_ENABLE, enable ? 2 : 0);
  
  #endif

-- 
Regards,

Laurent Pinchart