Re: [PATCH v2] mmc: mmci: use peripheral flow control for STM32

[Ulf Hansson]

On Thu, 28 Sept 2023 at 15:57, Ben Wolsieffer
<ben.wolsieffer@xxxxxxxxxxx> wrote:
>
> From: Ben Wolsieffer <Ben.Wolsieffer@xxxxxxxxxxx>
>
> The STM32 SDMMC peripheral (at least for the STM32F429, STM32F469 and
> STM32F746, which are all the currently supported devices using periphid
> 0x00880180) requires DMA to be performed in peripheral flow controller
> mode. From the STM32F74/5 reference manual, section 35.3.2:
>
> "SDMMC host allows only to use the DMA in peripheral flow controller
> mode. DMA stream used to serve SDMMC must be configured in peripheral
> flow controller mode"
>
> This patch adds a variant option to control peripheral flow control and
> enables it for the STM32 variant.
>
> Signed-off-by: Ben Wolsieffer <Ben.Wolsieffer@xxxxxxxxxxx>
> Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Applied for next, thanks!

Kind regards
Uffe


> ---
> Changes in v2: use bool instead of u8:1
>
>  drivers/mmc/host/mmci.c | 3 ++-
>  drivers/mmc/host/mmci.h | 2 ++
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index 769b34afa835..90e32f18abbc 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -249,6 +249,7 @@ static struct variant_data variant_stm32 = {
>         .f_max                  = 48000000,
>         .pwrreg_clkgate         = true,
>         .pwrreg_nopower         = true,
> +       .dma_flow_controller    = true,
>         .init                   = mmci_variant_init,
>  };
>
> @@ -1012,7 +1013,7 @@ static int _mmci_dmae_prep_data(struct mmci_host *host, struct mmc_data *data,
>                 .dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
>                 .src_maxburst = variant->fifohalfsize >> 2, /* # of words */
>                 .dst_maxburst = variant->fifohalfsize >> 2, /* # of words */
> -               .device_fc = false,
> +               .device_fc = variant->dma_flow_controller,
>         };
>         struct dma_chan *chan;
>         struct dma_device *device;
> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> index 253197f132fc..34d9897c289b 100644
> --- a/drivers/mmc/host/mmci.h
> +++ b/drivers/mmc/host/mmci.h
> @@ -332,6 +332,7 @@ enum mmci_busy_state {
>   * @opendrain: bitmask identifying the OPENDRAIN bit inside MMCIPOWER register
>   * @dma_lli: true if variant has dma link list feature.
>   * @stm32_idmabsize_mask: stm32 sdmmc idma buffer size.
> + * @dma_flow_controller: use peripheral as flow controller for DMA.
>   */
>  struct variant_data {
>         unsigned int            clkreg;
> @@ -378,6 +379,7 @@ struct variant_data {
>         u8                      dma_lli:1;
>         u32                     stm32_idmabsize_mask;
>         u32                     stm32_idmabsize_align;
> +       bool                    dma_flow_controller;
>         void (*init)(struct mmci_host *host);
>  };
>
> --
> 2.42.0
>