Re: [PATCH v3 0/9] R-Car Gen2 DMA Controller driver

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Magnus,

On Wednesday 29 October 2014 16:24:11 Magnus Damm wrote:
> On Mon, Oct 27, 2014 at 2:40 AM, Laurent Pinchart wrote:
> > Hello,
> > 
> > This patch sets adds a new driver for the DMA controller found in the
> > R-Car Gen2 SoCs under the name "Direct Memory Access Controller for System
> > (SYS-DMAC)". Support for the "Realtime Direct Memory Access Controller
> > (RT-DMAC)" and "Direct Memory Access Controller for Audio (Audio-DMAC)"
> > will be added later.
> > 
> > For the rationale of why a new driver is needed, and performance figures,
> > please see the cover letter of v1 ("[PATCH 0/7] R-Car Gen2 DMA Controller
> > driver") [1].
> > 
> > Support for hardware descriptors lists is not included in this series to
> > keep it simple and hopefully get it merged in v3.19. I'll post it as a
> > separate series. No change to the DT bindings will be needed.
> > 
> > The first three patches should go through the DMA engine tree, while the
> > last six patches should go through the Renesas tree. Simon, as the DT
> > bindings have been merged already, I believe you can queue up the arch
> > patches without waiting for the driver patches to be merged.
> > 
> > Known issues are
> > 
> > - Untested cyclic DMA transfers. I've done my best to fix the related
> >   issues from v2, but I haven't been able to test audio with the R-Car
> >   platforms (see [2]). Morimoto-san, if you could help me with audio
> >   testing I'd be grateful.
> >
> > - Stub system PM implementation. I'm working on this.
> > 
> > - Risk of conflict with Maxime's DMA engine rework series.
> > 
> > I believe the first two issues are not show stoppers. I can rebase the
> > patches if Maxime's patches get merged first.
> > 
> > Changes since v2:
> > 
> > - Replace several occurrences of size_t with unsigned int
> > - Remove unneeded local variable initialization
> > - Compute maximum transfer size at runtime
> > - Typo fixes
> > - Replace WARN_ON with WARN_ON_ONCE in interrupt handler
> > - Validate the number of channels
> > - Reset the device before enabling interrupts
> > - Use DMA_SLAVE_BUSWIDTH_* constants instead of numerical values
> > - Use devm_kasprintf
> > - Update to the new prep_dma_cyclic API
> > - Filter out channels from unrelated devices
> > - Fix typo in register definition
> > - Rename rcar_dmac_hw_desc to rcar_dmac_xfer_chunk
> > - Ignore the deprecated dma_slave_config direction field
> > - Allocate memory with GFP_NOWAIT in prep handlers
> > - Split runtime and system PM
> > - Move runtime PM to channel alloc/fre
> > 
> > Changes since v1:
> > 
> > - Allocate IRQ name strings dynamically
> > - Only call the callback function if one is supplied
> > - Don't overallocate sg list entries
> > - Allocate sg list entries with GFP_KERNEL
> > - Don't manage function clock manually
> > - Make channel filter ignore unrelated devices
> > - Document why the cyclic sg list is kcalloc'ed
> > - Remove ch15 from interrupt names in DT
> > - Replace CONFIG_OF with OF in Kconfig
> > 
> > [1] http://www.spinics.net/lists/linux-sh/msg33768.html
> > [2] http://www.spinics.net/lists/linux-sh/msg36474.html
> > 
> > Laurent Pinchart (9):
> >   dmaengine: Add 16 bytes, 32 bytes and 64 bytes bus widths
> >   dmaengine: rcar-dmac: Remove duplicate sentence from DT bindings
> >   dmaengine: rcar-dmac: Add Renesas R-Car Gen2 DMA Controller (DMAC)
> >   
> >     driver
> >   
> >   ARM: shmobile: r8a7790: Rename mmcif node to mmc
> >   ARM: shmobile: r8a7791: Add MMCIF0 DT node
> >   ARM: shmobile: r8a7790: Reference DMA channels in MMCIF DT nodes
> >   ARM: shmobile: r8a7791: Reference DMA channels in MMCIF DT node
> >   ARM: shmobile: r8a7790: Reference DMA channels in SDHI DT nodes
> >   ARM: shmobile: r8a7791: Reference DMA channels in SDHI DT nodes
> 
> Hi Laurent,
> 
> I've now tested this series briefly together with QSPI on Koelsch, and
> on top of that I've also done a prototype back port to LTSI-3.14. All
> seems well except this minor Kconfig adjustment that I needed to do to
> handle the case when we only enable this driver:
> 
> --- 0001/drivers/dma/Makefile
> +++ work/drivers/dma/Makefile 2014-10-29 13:14:24.000000000 +0900
> @@ -20,6 +20,7 @@ obj-$(CONFIG_AT_HDMAC) += at_hdmac.o
>  obj-$(CONFIG_MX3_IPU) += ipu/
>  obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
>  obj-$(CONFIG_SH_DMAE_BASE) += sh/
> +obj-$(CONFIG_RCAR_DMAC) += sh/
>  obj-$(CONFIG_COH901318) += coh901318.o coh901318_lli.o
>  obj-$(CONFIG_AMCC_PPC440SPE_ADMA) += ppc4xx/
>  obj-$(CONFIG_IMX_SDMA) += imx-sdma.o
> 
> Not the prettiest solution, but at least it makes the code compile
> regardless of SH_DMAE_BASE.
> Can you please consider folding this hunk into next version of your series?

How about this one instead ?

diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index cb626c179911..ebbcfdb8493a 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -18,7 +18,7 @@ obj-$(CONFIG_DW_DMAC_CORE) += dw/
 obj-$(CONFIG_AT_HDMAC) += at_hdmac.o
 obj-$(CONFIG_MX3_IPU) += ipu/
 obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
-obj-$(CONFIG_SH_DMAE_BASE) += sh/
+obj-$(CONFIG_RENESAS_DMA) += sh/
 obj-$(CONFIG_COH901318) += coh901318.o coh901318_lli.o
 obj-$(CONFIG_AMCC_PPC440SPE_ADMA) += ppc4xx/
 obj-$(CONFIG_IMX_SDMA) += imx-sdma.o
diff --git a/drivers/dma/sh/Kconfig b/drivers/dma/sh/Kconfig
index 6b4d95377bc8..8190ad225a1b 100644
--- a/drivers/dma/sh/Kconfig
+++ b/drivers/dma/sh/Kconfig
@@ -2,6 +2,10 @@
 # DMA engine configuration for sh
 #
 
+config RENESAS_DMA
+	bool
+	select DMA_ENGINE
+
 #
 # DMA Engine Helpers
 #
@@ -12,7 +16,7 @@ config SH_DMAE_BASE
 	depends on !SUPERH || SH_DMA
 	depends on !SH_DMA_API
 	default y
-	select DMA_ENGINE
+	select RENESAS_DMA
 	help
 	  Enable support for the Renesas SuperH DMA controllers.
 
@@ -56,7 +60,7 @@ config RCAR_AUDMAC_PP
 config RCAR_DMAC
 	tristate "Renesas R-Car Gen2 DMA Controller"
 	depends on ARCH_SHMOBILE || COMPILE_TEST
-	select DMA_ENGINE
+	select RENESAS_DMA
 	help
 	  This driver supports the general purpose DMA controller found in the
 	  Renesas R-Car second generation SoCs.

-- 
Regards,

Laurent Pinchart