Hi Matthieu, This patch didn't make it upstream. Kyungmin offered a suggestion for fixing it -- would you like to resend an updated patch?
(As a minor aside, I have a fairly irrational preference for "time_after(jiffies, timeout)" over "time_is_before_jiffies(timeout)", because the latter reads as the inverse of what it actually does to me. They compile to the same code.) Date: Thu, 17 Jun 2010 11:07:15 +0200 From: Matthieu CASTET <[email protected]> sdhci code got tasklets (sdhci_tasklet_card and sdhci_tasklet_finish), that does : { spin_lock_irqsave if (cond) { sdhci_reset sdhci_reset } spin_unlock_irqrestore } sdhci_reset { ... while (read_reg) { if (timeout == 0) break; timeout--; mdelay(1); } ... } The problem is that sdhci_reset [1] does busy pooling (with a granularity of 1 ms) on a register up to a timeout of 100 ms. With the current code, we got irq off during 2*1ms. With the attached patch we reduce irq off to 30 us. Note that worst case 100 ms irq off still exist. Signed-off-by: Matthieu CASTET <[email protected]> Signed-off-by: Chris Ball <[email protected]> --- diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index c6d1bd8..03d6bde 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -157,18 +157,17 @@ static void sdhci_reset(struct sdhci_host *host, u8 mask) host->clock = 0; /* Wait max 100 ms */ - timeout = 100; + timeout = jiffies + msecs_to_jiffies(100); /* hw clears the bit when it's done */ while (sdhci_readb(host, SDHCI_SOFTWARE_RESET) & mask) { - if (timeout == 0) { + if (time_is_before_jiffies(timeout)) { printk(KERN_ERR "%s: Reset 0x%x never completed.\n", mmc_hostname(host->mmc), (int)mask); sdhci_dumpregs(host); return; } - timeout--; - mdelay(1); + cpu_relax(); } if (host->quirks & SDHCI_QUIRK_RESTORE_IRQS_AFTER_RESET) @@ -882,7 +881,7 @@ static void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd) WARN_ON(host->cmd); /* Wait max 10 ms */ - timeout = 10; + timeout = jiffies + msecs_to_jiffies(10); mask = SDHCI_CMD_INHIBIT; if ((cmd->data != NULL) || (cmd->flags & MMC_RSP_BUSY)) @@ -894,7 +893,7 @@ static void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd) mask &= ~SDHCI_DATA_INHIBIT; while (sdhci_readl(host, SDHCI_PRESENT_STATE) & mask) { - if (timeout == 0) { + if (time_is_before_jiffies(timeout)) { printk(KERN_ERR "%s: Controller never released " "inhibit bit(s).\n", mmc_hostname(host->mmc)); sdhci_dumpregs(host); @@ -902,8 +901,7 @@ static void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd) tasklet_schedule(&host->finish_tasklet); return; } - timeout--; - mdelay(1); + cpu_relax(); } mod_timer(&host->timer, jiffies + 10 * HZ); @@ -1007,17 +1005,16 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock) sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL); /* Wait max 20 ms */ - timeout = 20; + timeout = jiffies + msecs_to_jiffies(20) while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL)) & SDHCI_CLOCK_INT_STABLE)) { - if (timeout == 0) { + if (time_is_before_jiffies(timeout)) { printk(KERN_ERR "%s: Internal clock never " "stabilised.\n", mmc_hostname(host->mmc)); sdhci_dumpregs(host); return; } - timeout--; - mdelay(1); + cpu_relax(); } clk |= SDHCI_CLOCK_CARD_EN; -- Chris Ball <[email protected]> <http://printf.net/> One Laptop Per Child -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
