On Fri, May 31, 2019 at 08:16:08PM +0900, Yoshihiro Shimoda wrote:
> This patch series is based on iommu.git / next branch.
> 
> Since SDHI host internal DMAC of the R-Car Gen3 cannot handle two or more
> segments, the performance rate (especially, eMMC HS400 reading) is not good.
> However, if IOMMU is enabled on the DMAC, since IOMMU will map multiple
> scatter gather buffers as one contignous iova, the DMAC can handle the iova
> as well and then the performance rate is possible to improve. In fact,
> I have measured the performance by using bonnie++, "Sequential Input - block"
> rate was improved on r8a7795.
> 
> However, in case of a sdio card (especiialy some WiFi cards/drivers),
> scatter gather buffers are possible to be not contiguous iova because
> each scatter gather buffer has only about 1500 bytes, the DMAC cannot
> handle it. So, this patch set adds init_card() ops to detect the card
> type, and then the driver changes the max_segs if the DMAC is under
> IOMMU environment and an sd card/mmc is detected.
> 
> Changes from v3 [1]:
>  - Use a helper function device_iommu_mapped on patch 1 and 3.
>  - Check if R-Car Gen3 IPMMU is used or not on patch 3.
>  - Check if all multiple segment buffers are aligned to PAGE_SIZE on patch 3.
>  - Add Reviewed-by Wolfram-san on patch 1 and 2. Note that I also got his
>    Reviewed-by on patch 3, but I changed it from v2. So, I didn't add
>    his Reviewed-by at this time.

Yes, dropping my rev on patch 3 is a good thing to do. I added Christoph
to the CC list because he gave valuable input last time.

@hch: If you didn't get the original mails from some list, I can bounce
them to you or you can find them here:

https://patchwork.kernel.org/project/linux-renesas-soc/list/?series=125593

> 
> Changes from v2 [2]:
>  - Add some conditions in the init_card().
>  - Add a comment in the init_card().
>  - Add definitions for some "MAX_SEGS".
> 
> Changes from v1 [3]:
>  - Remove adding init_card ops into struct tmio_mmc_dma_ops and
>    tmio_mmc_host and just set init_card on renesas_sdhi_core.c.
>  - Revise typos on "mmc: tmio: No memory size limitation if runs on IOMMU".
>  - Add Simon-san's Reviewed-by on a tmio patch.
> 
> [1]
> https://patchwork.kernel.org/project/linux-renesas-soc/list/?series=120985
> 
> [2]
> https://patchwork.kernel.org/project/linux-renesas-soc/list/?series=116729
> 
> [3]
> https://patchwork.kernel.org/project/linux-renesas-soc/list/?series=110485
> 
> 
> Yoshihiro Shimoda (3):
>   mmc: tmio: No memory size limitation if runs on IOMMU
>   mmc: tmio: Add a definition for default max_segs
>   mmc: renesas_sdhi: use multiple segments if possible
> 
>  drivers/mmc/host/renesas_sdhi.h               |  1 +
>  drivers/mmc/host/renesas_sdhi_core.c          | 60 +++++++++++++++++++++++++++
>  drivers/mmc/host/renesas_sdhi_internal_dmac.c | 19 +++++++++
>  drivers/mmc/host/tmio_mmc.h                   |  1 +
>  drivers/mmc/host/tmio_mmc_core.c              |  7 ++--
>  5 files changed, 85 insertions(+), 3 deletions(-)
> 
> -- 
> 2.7.4
>