Commits
Doug Anderson committed f8c58c11363
mmc: dw_mmc: Protect read-modify-write of INTMASK with a lock
We're running into cases where our enabling of the SDIO interrupt in
dw_mmc doesn't actually take effect. Specifically, adding patch like
this:
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1076,6 +1076,9 @@ static void dw_mci_enable_sdio_irq(struct mmc_host *mmc, int enb)
mci_writel(host, INTMASK,
(int_mask | SDMMC_INT_SDIO(slot->id)));
+ int_mask = mci_readl(host, INTMASK);
+ if (!(int_mask & SDMMC_INT_SDIO(slot->id)))
+ dev_err(&mmc->class_dev, "failed to enable sdio irq\n");
} else {
...actually triggers the error message. That's because the
dw_mci_enable_sdio_irq() unsafely does a read-modify-write of the
INTMASK register.
We can't just use the standard host->lock since that lock is not irq
safe and mmc_signal_sdio_irq() (called from interrupt context) calls
dw_mci_enable_sdio_irq(). Add a new irq-safe lock to protect INTMASK.
An alternate solution to this is to punt mmc_signal_sdio_irq() to the
tasklet and then protect INTMASK modifications by the standard host
lock. This seemed like a bit more of a high-latency change.
Reported-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>