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authorDoug Anderson <dianders@chromium.org>2014-12-03 02:42:47 +0300
committerUlf Hansson <ulf.hansson@linaro.org>2015-01-19 11:56:05 +0300
commitf8c58c1136349fdfa9b605c501f2f911622d3a9a (patch)
tree3f214e01a5ff8a1715dc8835a44406116146ef60 /include/linux/mmc
parentb24c8b260189fe21cca992d2f5175a33f6cc5477 (diff)
downloadlinux-f8c58c1136349fdfa9b605c501f2f911622d3a9a.tar.xz
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>
Diffstat (limited to 'include/linux/mmc')
-rw-r--r--include/linux/mmc/dw_mmc.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
index 42b724e8d503..471fb3116dbe 100644
--- a/include/linux/mmc/dw_mmc.h
+++ b/include/linux/mmc/dw_mmc.h
@@ -106,6 +106,11 @@ struct mmc_data;
* @cur_slot, @mrq and @state. These must always be updated
* at the same time while holding @lock.
*
+ * @irq_lock is an irq-safe spinlock protecting the INTMASK register
+ * to allow the interrupt handler to modify it directly. Held for only long
+ * enough to read-modify-write INTMASK and no other locks are grabbed when
+ * holding this one.
+ *
* The @mrq field of struct dw_mci_slot is also protected by @lock,
* and must always be written at the same time as the slot is added to
* @queue.
@@ -125,6 +130,7 @@ struct mmc_data;
*/
struct dw_mci {
spinlock_t lock;
+ spinlock_t irq_lock;
void __iomem *regs;
struct scatterlist *sg;