From e809517f6fa5803a5a1cd56026f0e2190fc13d5c Mon Sep 17 00:00:00 2001 From: Pierre Ossman Date: Fri, 25 Jul 2008 01:09:08 +0200 Subject: [PATCH] sdhci: let the controller wait for busy state to end The sdhci controllers can interrupt us when the busy state from the card has ended, saving CPU cycles and power. Signed-off-by: Pierre Ossman --- drivers/mmc/host/sdhci.c | 39 +++++++++++++++++++++++++++++++++------ 1 file changed, 33 insertions(+), 6 deletions(-) diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index e3a8133560a..ef461274397 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -1266,9 +1266,31 @@ static void sdhci_cmd_irq(struct sdhci_host *host, u32 intmask) SDHCI_INT_INDEX)) host->cmd->error = -EILSEQ; - if (host->cmd->error) + if (host->cmd->error) { tasklet_schedule(&host->finish_tasklet); - else if (intmask & SDHCI_INT_RESPONSE) + return; + } + + /* + * The host can send and interrupt when the busy state has + * ended, allowing us to wait without wasting CPU cycles. + * Unfortunately this is overloaded on the "data complete" + * interrupt, so we need to take some care when handling + * it. + * + * Note: The 1.0 specification is a bit ambiguous about this + * feature so there might be some problems with older + * controllers. + */ + if (host->cmd->flags & MMC_RSP_BUSY) { + if (host->cmd->data) + DBG("Cannot wait for busy signal when also " + "doing a data transfer"); + else + return; + } + + if (intmask & SDHCI_INT_RESPONSE) sdhci_finish_command(host); } @@ -1278,11 +1300,16 @@ static void sdhci_data_irq(struct sdhci_host *host, u32 intmask) if (!host->data) { /* - * A data end interrupt is sent together with the response - * for the stop command. + * The "data complete" interrupt is also used to + * indicate that a busy state has ended. See comment + * above in sdhci_cmd_irq(). */ - if (intmask & SDHCI_INT_DATA_END) - return; + if (host->cmd && (host->cmd->flags & MMC_RSP_BUSY)) { + if (intmask & SDHCI_INT_DATA_END) { + sdhci_finish_command(host); + return; + } + } printk(KERN_ERR "%s: Got data interrupt 0x%08x even " "though no data operation was in progress.\n", -- 2.20.1