mmc: mmci: use peripheral flow control for STM32

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@hefring.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230928135644.1489691-1-ben.wolsieffer@hefring.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index dda756a5637936cd28f195b53aa52824454825a4..e967cca7a16f908a6f70710e391f1035fcf16e49 100644 (file)
--- 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,
 };
 
@@ -1015,7 +1016,7 @@ 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 253197f132fca786e6099ad927ce8d7a307b9dc7..34d9897c289b3fc7dd4c88412ba9e00767564737 100644 (file)
--- 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);
 };