Re: [PATCH] mmc: mmci: add variant property to send stop cmd if a command fail

From: Ulf Hansson
Date: Wed Oct 31 2018 - 11:17:12 EST

On 30 October 2018 at 11:16, Ludovic Barre <ludovic.Barre@xxxxxx> wrote:
> From: Ludovic Barre <ludovic.barre@xxxxxx>
>
> The mmc framework follows the requirement of SD_Specification:
> the STOP_TRANSMISSION is sent on multiple write/read commands
> and the stop command (alone), not needed on other ADTC commands.

Well, there is a bit more to it than that.

Host drivers may set MMC_CAP_CMD23 support, which means pre-defined
multi-block transfers, becomes preferable to open-ended ones.

However, even for pre-defined transfers, a CM12 (stop transmission)
should be sent, in case of data transfer errors. At least if I
understand the specs correctly.

By looking at the code in mmci_data_irq(), I realize that it's not
considering this case - so I think that need to be fixed as to start
with.

>
> But, if an error happens on command or data step, some variants
> require a stop command "STOP_TRANSMISION" to clear the DPSM
> "Data Path State Machine". If it's not done the next data
> command freezes hardware block.
> Needed to support the STM32 sdmmc variant.

I don't really follow this, sorry. Could you start by clarifying what
you mean by "data step", according to the above?

As far as I understand, you need to send a CMD12 to clear the DPSM, in
case of any errors happening during a data transfer (which includes
ADTC commands as well), right?

Or is there anything else to it?

Kind regards
Uffe

>
> Signed-off-by: Ludovic Barre <ludovic.barre@xxxxxx>
> ---
> drivers/mmc/host/mmci.c | 33 +++++++++++++++++++++++++++++++++
> drivers/mmc/host/mmci.h | 4 ++++
> 2 files changed, 37 insertions(+)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index 19650ed..ecedca3 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -21,6 +21,7 @@
> #include <linux/err.h>
> #include <linux/highmem.h>
> #include <linux/log2.h>
> +#include <linux/mmc/mmc.h>
> #include <linux/mmc/pm.h>
> #include <linux/mmc/host.h>
> #include <linux/mmc/card.h>
> @@ -57,6 +58,8 @@ void sdmmc_variant_init(struct mmci_host *host);
> #else
> static inline void sdmmc_variant_init(struct mmci_host *host) {}
> #endif
> +static void
> +mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c);
>
> static unsigned int fmax = 515633;
>
> @@ -274,6 +277,7 @@ static struct variant_data variant_stm32_sdmmc = {
> .cmdreg_lrsp_crc = MCI_CPSM_STM32_LRSP_CRC,
> .cmdreg_srsp_crc = MCI_CPSM_STM32_SRSP_CRC,
> .cmdreg_srsp = MCI_CPSM_STM32_SRSP,
> + .cmdreg_stop = MCI_CPSM_STM32_CMDSTOP,
> .data_cmd_enable = MCI_CPSM_STM32_CMDTRANS,
> .irq_pio_mask = MCI_IRQ_PIO_STM32_MASK,
> .datactrl_first = true,
> @@ -574,6 +578,24 @@ void mmci_dma_error(struct mmci_host *host)
> static void
> mmci_request_end(struct mmci_host *host, struct mmc_request *mrq)
> {
> + /*
> + * If an error happens on command or data step, some variants
> + * require a stop command to reinit the DPSM.
> + * If it's not done the next data command freeze hardware block.
> + */
> + if (host->variant->cmdreg_stop) {
> + u32 dpsm;
> +
> + dpsm = readl_relaxed(host->base + MMCISTATUS);
> + dpsm &= MCI_STM32_DPSMACTIVE;
> +
> + if (dpsm && ((mrq->cmd && mrq->cmd->error) ||
> + (mrq->data && mrq->data->error))) {
> + mmci_start_command(host, &host->stop_abort, 0);
> + return;
> + }
> + }
> +
> writel(0, host->base + MMCICOMMAND);
>
> BUG_ON(host->data);
> @@ -1106,6 +1128,10 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c)
> mmci_reg_delay(host);
> }
>
> + if (host->variant->cmdreg_stop &&
> + cmd->opcode == MMC_STOP_TRANSMISSION)
> + c |= host->variant->cmdreg_stop;
> +
> c |= cmd->opcode | host->variant->cmdreg_cpsm_enable;
> if (cmd->flags & MMC_RSP_PRESENT) {
> if (cmd->flags & MMC_RSP_136)
> @@ -1957,6 +1983,13 @@ static int mmci_probe(struct amba_device *dev,
> mmc->max_busy_timeout = 0;
> }
>
> + /* prepare the stop command, used to abort and reinitialized the DPSM */
> + if (variant->cmdreg_stop) {
> + host->stop_abort.opcode = MMC_STOP_TRANSMISSION;
> + host->stop_abort.arg = 0;
> + host->stop_abort.flags = MMC_RSP_R1B | MMC_CMD_AC;
> + }
> +
> mmc->ops = &mmci_ops;
>
> /* We support these PM capabilities. */
> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> index ec13d90..afb6ec4 100644
> --- a/drivers/mmc/host/mmci.h
> +++ b/drivers/mmc/host/mmci.h
> @@ -166,6 +166,7 @@
> #define MCI_ST_CEATAEND (1 << 23)
> #define MCI_ST_CARDBUSY (1 << 24)
> /* Extended status bits for the STM32 variants */
> +#define MCI_STM32_DPSMACTIVE BIT(12)
> #define MCI_STM32_BUSYD0 BIT(20)
>
> #define MMCICLEAR 0x038
> @@ -269,6 +270,7 @@ struct mmci_host;
> * @cmdreg_lrsp_crc: enable value for long response with crc
> * @cmdreg_srsp_crc: enable value for short response with crc
> * @cmdreg_srsp: enable value for short response without crc
> + * @cmdreg_stop: enable value for stop and abort transmission
> * @datalength_bits: number of bits in the MMCIDATALENGTH register
> * @fifosize: number of bytes that can be written when MMCI_TXFIFOEMPTY
> * is asserted (likewise for RX)
> @@ -322,6 +324,7 @@ struct variant_data {
> unsigned int cmdreg_lrsp_crc;
> unsigned int cmdreg_srsp_crc;
> unsigned int cmdreg_srsp;
> + unsigned int cmdreg_stop;
> unsigned int datalength_bits;
> unsigned int fifosize;
> unsigned int fifohalfsize;
> @@ -384,6 +387,7 @@ struct mmci_host {
> void __iomem *base;
> struct mmc_request *mrq;
> struct mmc_command *cmd;
> + struct mmc_command stop_abort;
> struct mmc_data *data;
> struct mmc_host *mmc;
> struct clk *clk;
> --
> 2.7.4
>