[PATCH v5 4/5] mmc: core: Add sdio_retune_hold_now() and sdio_retune_release()

From: Douglas Anderson
Date: Mon Jun 17 2019 - 14:04:17 EST


We want SDIO drivers to be able to temporarily stop retuning when the
driver knows that the SDIO card is not in a state where retuning will
work (maybe because the card is asleep). We'll move the relevant
functions to a place where drivers can call them.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
Patches #2 - #5 will go through Ulf's tree.

I've CCed stable@ here without a version tag. As per Adrian Hunter
this patch applies cleanly to 4.18+ so that would be an easy first
target. However, if someone were so inclined they could provide
further backports. As per Adrian [1] the root problem has existed for
~4 years.

[1] https://lkml.kernel.org/r/4f39e152-04ba-a64e-985a-df93e6d15ff8@xxxxxxxxx

Changes in v5: None
Changes in v4:
- Moved retune hold/release to SDIO API (Adrian).

Changes in v3:
- ("mmc: core: Export mmc_retune_hold_now() mmc_retune_release()") new for v3.

Changes in v2: None

drivers/mmc/core/sdio_io.c | 40 +++++++++++++++++++++++++++++++++++
include/linux/mmc/sdio_func.h | 3 +++
2 files changed, 43 insertions(+)

diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
index 0acb1a29c968..2ba00acf64e6 100644
--- a/drivers/mmc/core/sdio_io.c
+++ b/drivers/mmc/core/sdio_io.c
@@ -15,6 +15,7 @@
#include "sdio_ops.h"
#include "core.h"
#include "card.h"
+#include "host.h"

/**
* sdio_claim_host - exclusively claim a bus for a certain SDIO function
@@ -771,3 +772,42 @@ void sdio_retune_crc_enable(struct sdio_func *func)
func->card->host->retune_crc_disable = false;
}
EXPORT_SYMBOL_GPL(sdio_retune_crc_enable);
+
+/**
+ * sdio_retune_hold_now - start deferring retuning requests till release
+ * @func: SDIO function attached to host
+ *
+ * This function can be called if it's currently a bad time to do
+ * a retune of the SDIO card. Retune requests made during this time
+ * will be held and we'll actually do the retune sometime after the
+ * release.
+ *
+ * This function could be useful if an SDIO card is in a power state
+ * where it can respond to a small subset of commands that doesn't
+ * include the retuning command. Care should be taken when using
+ * this function since (presumably) the retuning request we might be
+ * deferring was made for a good reason.
+ *
+ * This function should be called while the host is claimed.
+ */
+void sdio_retune_hold_now(struct sdio_func *func)
+{
+ mmc_retune_hold_now(func->card->host);
+}
+EXPORT_SYMBOL_GPL(sdio_retune_hold_now);
+
+/**
+ * sdio_retune_release - signal that it's OK to retune now
+ * @func: SDIO function attached to host
+ *
+ * This is the complement to sdio_retune_hold_now(). Calling this
+ * function won't make a retune happen right away but will allow
+ * them to be scheduled normally.
+ *
+ * This function should be called while the host is claimed.
+ */
+void sdio_retune_release(struct sdio_func *func)
+{
+ mmc_retune_release(func->card->host);
+}
+EXPORT_SYMBOL_GPL(sdio_retune_release);
diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
index 4820e6d09dac..5a177f7a83c3 100644
--- a/include/linux/mmc/sdio_func.h
+++ b/include/linux/mmc/sdio_func.h
@@ -170,4 +170,7 @@ extern int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags);
extern void sdio_retune_crc_disable(struct sdio_func *func);
extern void sdio_retune_crc_enable(struct sdio_func *func);

+extern void sdio_retune_hold_now(struct sdio_func *func);
+extern void sdio_retune_release(struct sdio_func *func);
+
#endif /* LINUX_MMC_SDIO_FUNC_H */
--
2.22.0.410.gd8fdbe21b5-goog