Subject: [PATCH v7 0/9] Fix broken DMAFLUSHP on Rockchips platform

From: [email-masked] (Caesar Wang)
Date: Mon, 1 Feb 2016 14:56:54 +0800

Hello Vinod,

Is there any chance apply the DMA patches?:-)

-
Caesar

? 2016?01?22? 19:06, Caesar Wang ??:
> This series patches are apply on linus master branch.
> Okay, this series patches verified on my github.
> (https://github.com/Caesar-github/rockchip/commits/for-dma-tests)
>
> Linux version 4.4.0+ (wxt at ubuntu)  (Ubuntu/Linaro 4.7.3-12ubuntu1) ) #14
> SMP Fri Jan 22 18:13:12 CST 2016
>
> The perious version 6 from Shawn.
> (http://www.spinics.net/lists/dmaengine/msg06606.html)
> I pick them up to go on upstream since Shawn hasn't much time to track them.
> ----
>
> 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.
>
> Todo:
> remove the patches releated to i2s, that will send them at later.
> - https://patchwork.kernel.org/patch/7399581/
> - https://patchwork.kernel.org/patch/7399671/
>
>
> Changes in v7:
> - As vinod comments, fix the subsystem name.
> - modify the subject to be better match.
> - fix the subsystem.
> - fix the subject.
> - fix the subject.
>
> Changes in v6:
> - remove expose quirk and add dma max_burst caps for clients
> - remove expose quirks and add max_burst for dmaengine
> - remove quirks and get dma caps in order to limit burst
>
> Changes in v5:
> - add Mark's tag for spi changes
> - remove unnecessary whitespace change
> - use switch statement for i2s quirk
>
> 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]>
> - add Reviewed-by: Sonny Rao <[email-masked]>
> - 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
> - add Reviewed-by: Doug Anderson <[email-masked]>
> - amend the author
> - fix Olof's mail address
> - amend the author
> - add Reviewed-by: Doug Anderson <[email-masked]>
> - 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
> - rename broken-no-flushp to "arm,pl330-broken-no-flushp" suggested
>    by Krzysztof.
> - rename broken-no-flushp to "arm,pl330-broken-no-flushp" suggested
>    by Krzysztof.
> - remove Sunny's tag
> - rename broken-no-flushp to "arm,pl330-broken-no-flushp" suggested
>    by Krzysztof.
>    - remove Sunny's tag
> - rename broken-no-flushp to "arm,pl330-broken-no-flushp" suggested
>    by Krzysztof.
>
> Addy Ke (3):
>    dmaengine: 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):
>    dmaengine: pl330: support burst mode for dev-to-mem and mem-to-dev
>      transmit
>
> Caesar Wang (1):
>    ARM: dts: add pl330-broken-no-flushp quirk for rk3036 SoCs
>
> Shawn Lin (4):
>    dt/bindings: arm-pl330: add description of arm, pl330-broken-no-flushp
>    ARM: dts: Add arm, pl330-broken-no-flushp quirk for rk3xxx platform
>    dmaengine: core: expose max burst capability to clients
>    dmaengine: pl330: add max burst for dmaengine
>
>   .../devicetree/bindings/dma/arm-pl330.txt          |   1 +
>   arch/arm/boot/dts/rk3036.dtsi                      |   1 +
>   arch/arm/boot/dts/rk3288.dtsi                      |   3 +
>   arch/arm/boot/dts/rk3xxx.dtsi                      |   3 +
>   drivers/dma/dmaengine.c                            |   1 +
>   drivers/dma/pl330.c                                | 106 +++++++++++++++------
>   drivers/spi/spi-rockchip.c                         |  12 ++-
>   include/linux/dmaengine.h                          |   4 +
>   8 files changed, 99 insertions(+), 32 deletions(-)
>

-- 
Thanks,
Caesar