Re: [PATCH v2 6/8] mmc: sdhci-pxav2: add SDIO card IRQ workaround for PXA168 V1 controller

[Adrian Hunter <adrian.hunter@intel.com>]

On 2/12/22 05:13, Doug Brown wrote:
> The PXA168 has a documented silicon bug that causes SDIO card IRQs to be
> missed. Implement the first half of the suggested workaround, which
> involves resetting the data port logic and issuing a dummy CMD0 to
> restart the clock.
> 
> Signed-off-by: Doug Brown <doug@schmorgal.com>
> ---
>  drivers/mmc/host/sdhci-pxav2.c | 49 ++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-pxav2.c b/drivers/mmc/host/sdhci-pxav2.c
> index 1f0c3028987a..912b2aad9f2e 100644
> --- a/drivers/mmc/host/sdhci-pxav2.c
> +++ b/drivers/mmc/host/sdhci-pxav2.c
> @@ -20,6 +20,8 @@
>  #include <linux/slab.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/mmc/sdio.h>
> +#include <linux/mmc/mmc.h>
>  
>  #include "sdhci.h"
>  #include "sdhci-pltfm.h"
> @@ -43,6 +45,7 @@
>  
>  struct sdhci_pxav2_host {
>  	struct clk *clk_core;
> +	struct mmc_request *sdio_mrq;
>  };
>  
>  static void pxav2_reset(struct sdhci_host *host, u8 mask)
> @@ -93,6 +96,50 @@ static u16 pxav1_readw(struct sdhci_host *host, int reg)
>  	return readw(host->ioaddr + reg);
>  }
>  
> +static u32 pxav1_irq(struct sdhci_host *host, u32 intmask)
> +{
> +	struct sdhci_pxav2_host *pxav2_host = sdhci_pltfm_priv(sdhci_priv(host));
> +
> +	if (pxav2_host->sdio_mrq && (intmask & SDHCI_INT_CMD_MASK)) {
> +		/* The dummy CMD0 for the SDIO workaround just completed */
> +		sdhci_writel(host, intmask & SDHCI_INT_CMD_MASK, SDHCI_INT_STATUS);
> +		intmask &= ~SDHCI_INT_CMD_MASK;
> +		mmc_request_done(host->mmc, pxav2_host->sdio_mrq);
> +		pxav2_host->sdio_mrq = NULL;

Pedantically, things should be finished before calling
mmc_request_done() i.e. last 2 line the other way around

		pxav2_host->sdio_mrq = NULL;
		mmc_request_done(host->mmc, pxav2_host->sdio_mrq);

> +	}
> +
> +	return intmask;
> +}
> +
> +static void pxav1_request_done(struct sdhci_host *host, struct mmc_request *mrq)
> +{
> +	u16 tmp;
> +	struct sdhci_pxav2_host *pxav2_host;
> +
> +	/* If this is an SDIO command, perform errata workaround for silicon bug */
> +	if (mrq->cmd && !mrq->cmd->error &&
> +	    (mrq->cmd->opcode == SD_IO_RW_DIRECT ||
> +	     mrq->cmd->opcode == SD_IO_RW_EXTENDED)) {
> +		/* Reset data port */
> +		tmp = readw(host->ioaddr + SDHCI_TIMEOUT_CONTROL);
> +		tmp |= 0x400;
> +		writew(tmp, host->ioaddr + SDHCI_TIMEOUT_CONTROL);
> +
> +		/* Clock is now stopped, so restart it by sending a dummy CMD0 */
> +		pxav2_host = sdhci_pltfm_priv(sdhci_priv(host));
> +		pxav2_host->sdio_mrq = mrq;
> +		sdhci_writel(host, 0, SDHCI_ARGUMENT);
> +		sdhci_writew(host, 0, SDHCI_TRANSFER_MODE);
> +		sdhci_writew(host, SDHCI_MAKE_CMD(MMC_GO_IDLE_STATE, SDHCI_CMD_RESP_NONE),
> +			     SDHCI_COMMAND);
> +
> +		/* Don't finish this request until the dummy CMD0 finishes */
> +		return;
> +	}
> +
> +	mmc_request_done(host->mmc, mrq);
> +}
> +
>  static void pxav2_mmc_set_bus_width(struct sdhci_host *host, int width)
>  {
>  	u8 ctrl;
> @@ -117,10 +164,12 @@ static void pxav2_mmc_set_bus_width(struct sdhci_host *host, int width)
>  static const struct sdhci_ops pxav1_sdhci_ops = {
>  	.read_w        = pxav1_readw,
>  	.set_clock     = sdhci_set_clock,
> +	.irq           = pxav1_irq,
>  	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
>  	.set_bus_width = pxav2_mmc_set_bus_width,
>  	.reset         = pxav2_reset,
>  	.set_uhs_signaling = sdhci_set_uhs_signaling,
> +	.request_done  = pxav1_request_done,
>  };
>  
>  static const struct sdhci_ops pxav2_sdhci_ops = {