Subject: [PATCH v5 0/10] Fix broken DMAFLUSHP on Rockchips platform

From: [email-masked] (Shawn Lin)
Date: Mon, 28 Sep 2015 09:59:25 +0800

Hi Vinod,

	Is there any chance for this patchset to be applied? :)

On 2015/9/14 7:45, Shawn Lin wrote:
> The purpose of the DMAFLUSHP instruction:
> - Tell the peripheral to clear its status and control registers.
> - Send a message to the peripheral to resend its level status.
>
> There are 3 timings described in PL330 Technical Reference Manual:
> - Timing 1: Burst request, can work well without DMAFLUSHP.
> - Timing 2: Single and burst request, DMAC will ignore the single
> 	    transfer request. This timing happens if there are single
> 	    and burst request.
> - Timing 3: Single transfers for a burst request, DMAC should signals
> 	    datype to request the peripheral to flush the contents of
> 	    any control registers. This timing happens if there is
> 	    not enough MFIFO to places the burst data.
>
> A peripheral may signal a DMA request during the execution of
> DMAFLUSHP instruction, that cause DMA request being ignored by DMAC.
>
> But DMAC and all peripherals on RK3X SoCs DO NOT support DMAFLUSHP.
> It can't send a message to the peripheral to resend DMA request,
> and the peripheral can't acknowledge a flush request from DMAC.
> So all DMA requests should NOT be ignored by DMAC, and DMAC will not
> notify the peripheral to flush.
>
> To fix this problem, we need:
> - Do NOT execute DMAFLUSHP instruction.
> - Timing 2 and timing 3 should not happen.
>
> Because on RK3X SoCs, there are 6 or below  channels and 32 MFIFO depth
> for DMAC_BUS, and 8 channels and 64 MFIFO depth for DMAC_PERI, it is
> impossible to hit the timing 3 if burst length is equal or less than 4.
>
> Since the request type signal by the peripheral can only be set by
> software. We can set Rockchip Soc's GRF_PERIDMAC_CON0[2:1] to select single
> or burst request, if it is set b01,  all of the peripharals will signal a brust
> request. So the timing 2 will not happen, too.
>
> So DMAC on RK3X can support single or burst transfer, but can't support
> mixed transfer.
>
> Because burst transfer is more efficient than single transfer, this is
> confirmed by our ASIC team, who strongly suggest to use burst transfer.
> And this is confirmed by Addy's test on RK3288-Pink2 board, the speed of
> spi flash burst transfer will increase about two times than single transfer.
> Also, I have tested dw_mmc with pl330 on RK3188 platform to double confirm
> the result. That means burst transfer is reansonable.
>
> So we need a quirk not to execute DMAFLUSHP instruction and to use burst
> transfer.
>
> Note:
> - The Rockchip Soc default value of GRF_PERIDMAC_CON0[2:1] is b01. To
>    support brust transfer, these bits should not be changed in bootloader.
>
>
> Changes in v5:
> - add Mark's tag for spi changes
> - remove unnecessary whitespace change
> - use switch statement for I2S dma_quirk's manipulation
>
> Changes in v4:
> - remove spi & i2s dts changes and query quirk from dmaengine API
>    suggeseted by Mark.
> - fix typo
> - Add dmaengine_get_quirk hook and implement it for pl330
>
> Changes in v3:
> - add Sunny's tag
> - add more rockchip drivers' changes in this patchset
> - add Reviewed-by: Sonny Rao <[email-masked]>
>
> Changes in v2:
> - amend the author
> - reorder the patches suggested by Doug
> - add Reviewed-by: Doug Anderson <[email-masked]> for
>    rk3288.dtsi patch and arm-pl330.txt patch
> - amend Olof's mail address
>
> Changes in v1:
> - rename broken-no-flushp to "arm,pl330-broken-no-flushp" suggested
>    by Krzysztof.
> - add From original author.
> - remove Sunny's tag
>
> Addy Ke (3):
>    DMA: pl330: add quirk for broken no flushp
>    ARM: dts: Add arm,pl330-broken-no-flushp quirk for rk3288 platform
>    spi: rockchip: modify DMA max burst to 1
>
> Boojin Kim (1):
>    DMA: pl330: support burst mode for dev-to-mem and mem-to-dev transmit
>
> Shawn Lin (5):
>    Documentation: arm-pl330: add description of
>      arm,pl330-broken-no-flushp
>    ARM: dts: Add arm,pl330-broken-no-flushp quirk for rk3xxx platform
>    dmaengine: add API for getting dma controller's quirk
>    DMA: pl330: implement dmaengine_get_quirks hook
>    snd: dmaengine-pcm: add snd_dmaengine_pcm_get_quirks interface
>
> Yiwei Cai (1):
>    ASoC: rockchip_i2s: modify DMA max burst to 1
>
>   .../devicetree/bindings/dma/arm-pl330.txt          |   1 +
>   arch/arm/boot/dts/rk3288.dtsi                      |   3 +
>   arch/arm/boot/dts/rk3xxx.dtsi                      |   3 +
>   drivers/dma/pl330.c                                | 110 +++++++++++++++------
>   drivers/spi/spi-rockchip.c                         |  13 ++-
>   include/linux/dmaengine.h                          |   9 ++
>   sound/soc/rockchip/rockchip_i2s.c                  |  21 ++++
>   sound/soc/soc-generic-dmaengine-pcm.c              |  24 +++++
>   8 files changed, 153 insertions(+), 31 deletions(-)
>

-- 
Best Regards
Shawn Lin