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SubjectRe: [PATCH 1/4] mmc: mmci: avoid fake busy polling
On Tue, 5 Mar 2019 at 17:10, Ludovic Barre <ludovic.Barre@st.com> wrote:
>
> From: Ludovic Barre <ludovic.barre@st.com>
>
> The busy status bit could occurred even if no busy response is
> expected (example cmd11). On sdmmc variant, the busy_detect_flag
> reflects inverted value of d0 state, it's sampled at the end of a
> CMD response and a second time 2 clk cycles after the CMD response.
> To avoid a fake busy, the busy status could be checked and polled
> only if the command has RSP_BUSY flag.
>
> Signed-off-by: Ludovic Barre <ludovic.barre@st.com>

Before I review this, can you tell what HW you have tested this on?

Kind regards
Uffe

> ---
> drivers/mmc/host/mmci.c | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index 387ff14..4901b73 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -1220,12 +1220,13 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
> unsigned int status)
> {
> void __iomem *base = host->base;
> - bool sbc;
> + bool sbc, busy_resp;
>
> if (!cmd)
> return;
>
> sbc = (cmd == host->mrq->sbc);
> + busy_resp = !!(cmd->flags & MMC_RSP_BUSY);
>
> /*
> * We need to be one of these interrupts to be considered worth
> @@ -1239,8 +1240,7 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
> /*
> * ST Micro variant: handle busy detection.
> */
> - if (host->variant->busy_detect) {
> - bool busy_resp = !!(cmd->flags & MMC_RSP_BUSY);
> + if (busy_resp && host->variant->busy_detect) {
>
> /* We are busy with a command, return */
> if (host->busy_status &&
> @@ -1253,7 +1253,7 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
> * that the special busy status bit is still set before
> * proceeding.
> */
> - if (!host->busy_status && busy_resp &&
> + if (!host->busy_status &&
> !(status & (MCI_CMDCRCFAIL|MCI_CMDTIMEOUT)) &&
> (readl(base + MMCISTATUS) & host->variant->busy_detect_flag)) {
>
> @@ -1508,6 +1508,7 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
> {
> struct mmci_host *host = dev_id;
> u32 status;
> + bool busy_resp;
> int ret = 0;
>
> spin_lock(&host->lock);
> @@ -1550,9 +1551,15 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
> }
>
> /*
> - * Don't poll for busy completion in irq context.
> + * Don't poll for:
> + * -busy completion in irq context.
> + * -no busy response expected.
> */
> - if (host->variant->busy_detect && host->busy_status)
> + busy_resp = host->cmd ?
> + !!(host->cmd->flags & MMC_RSP_BUSY) : false;
> +
> + if (host->variant->busy_detect &&
> + (!busy_resp || host->busy_status))
> status &= ~host->variant->busy_detect_flag;
>
> ret = 1;
> --
> 2.7.4
>

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