mmc: core: Add support for idle time BKOPS
Devices have various maintenance operations need to perform internally.
In order to reduce latencies during time critical operations like read
and write, it is better to execute maintenance operations in other
times - when the host is not being serviced. Such operations are called
Background operations (BKOPS).
The device notifies the status of the BKOPS need by updating BKOPS_STATUS
(EXT_CSD byte [246]).
According to the standard a host that supports BKOPS shall check the
status periodically and start background operations as needed, so that
the device has enough time for its maintenance operations.
This patch adds support for this periodic check of the BKOPS status.
Since foreground operations are of higher priority than background
operations the host will check the need for BKOPS when it is idle,
and in case of an incoming request the BKOPS operation will be
interrupted.
When the mmcqd thread is idle, a delayed work is created to check the
need for BKOPS. The time to start the delayed work is calculated based
on the host controller suspend timeout, in case it was set. If not, a
default time is used.
If BKOPS are required in level 1, which is non-blocking, there will be
polling of the card status to wait for the BKOPS completion and prevent
suspend that will interrupt the BKOPS.
If the card raised an exception, the need for urgent BKOPS (level 2/3)
will be checked immediately and if needed, the BKOPS will be performed
without waiting for the next idle time.
(cherry picked from commit 5f360698caa2894f7cc854199ffba285241d152e)
Change-Id: I6605ce396188807bed93f437224f2243b178523f
Signed-off-by: Maya Erez <merez@codeaurora.org>
(cherry picked from commit 833940e728c5903f0263c20e349bbead7a79e535)
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 6bb86c2..257bcc0 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -229,6 +229,48 @@
#define MMC_BLK_DATA_AREA_GP (1<<2)
};
+/**
+ * struct mmc_bkops_info - BKOPS data
+ * @dw: Idle time bkops delayed work
+ * @host_suspend_tout_ms: The host controller idle time,
+ * before getting into suspend
+ * @delay_ms: The time to start the BKOPS
+ * delayed work once MMC thread is idle
+ * @poll_for_completion: Poll on BKOPS completion
+ * @cancel_delayed_work: A flag to indicate if the delayed work
+ * should be cancelled
+ * @started_delayed_bkops: A flag to indicate if the delayed
+ * work was scheduled
+ * @sectors_changed: number of sectors written or
+ * discard since the last idle BKOPS were scheduled
+ */
+struct mmc_bkops_info {
+ struct delayed_work dw;
+ unsigned int host_suspend_tout_ms;
+ unsigned int delay_ms;
+/*
+ * A default time for checking the need for non urgent BKOPS once mmcqd
+ * is idle.
+ */
+#define MMC_IDLE_BKOPS_TIME_MS 2000
+ struct work_struct poll_for_completion;
+/* Polling timeout and interval for waiting on non-blocking BKOPs completion */
+#define BKOPS_COMPLETION_POLLING_TIMEOUT_MS 10000 /* in ms */
+#define BKOPS_COMPLETION_POLLING_INTERVAL_MS 1000 /* in ms */
+ bool cancel_delayed_work;
+ bool started_delayed_bkops;
+ unsigned int sectors_changed;
+/*
+ * Since canceling the delayed work might have significant effect on the
+ * performance of small requests we won't queue the delayed work every time
+ * mmcqd thread is idle.
+ * The delayed work for idle BKOPS will be scheduled only after a significant
+ * amount of write or discard data.
+ * 100MB is chosen based on benchmark tests.
+ */
+#define BKOPS_MIN_SECTORS_TO_QUEUE_DELAYED_WORK 204800 /* 100MB */
+};
+
/*
* MMC device
*/
@@ -304,6 +346,8 @@
unsigned int nr_parts;
struct mmc_wr_pack_stats wr_pack_stats; /* packed commands stats*/
+
+ struct mmc_bkops_info bkops_info;
};
/*