Previously there has only been one function mmc_wait_for_req
to start and wait for a request. This patch adds
* mmc_start_req - starts a request wihtout waiting
* mmc_wait_for_req_done - waits until request is done
* mmc_pre_req - asks the host driver to prepare for the next job
* mmc_post_req - asks the host driver to clean up after a completed job
The intention is to use pre_req() and post_req() to do cache maintenance
while a request is active. pre_req() can be called while a request is active
to minimize latency to start next job. post_req() can be used after the next
job is started to clean up the request. This will minimize the host driver
request end latency. post_req() is typically used before ending the block
request and handing over the buffer to the block layer.
Add a host-private member in mmc_data to be used by
pre_req to mark the data. The host driver will then
check this mark to see if the data is prepared or not.
Signed-off-by: Per Forlin <per.for...@linaro.org>
---
drivers/mmc/core/core.c | 78 ++++++++++++++++++++++++++++++++++++++++------
include/linux/mmc/core.h | 9 +++++-
include/linux/mmc/host.h | 9 +++++
3 files changed, 85 insertions(+), 11 deletions(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 1f453ac..e88dd36 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -198,30 +198,88 @@ mmc_start_request(struct mmc_host *host, struct
mmc_request *mrq)
static void mmc_wait_done(struct mmc_request *mrq)
{
- complete(mrq->done_data);
+ complete(&mrq->completion);
}
/**
- * mmc_wait_for_req - start a request and wait for completion
+ * mmc_pre_req - Prepare for a new request
+ * @host: MMC host to prepare command
+ * @mrq: MMC request to prepare for
+ * @is_first_req: true if there is no previous started request
+ * that may run in parellel to this call, otherwise false
+ *
+ * mmc_pre_req() is called in prior to mmc_start_req() to let
+ * host prepare for the new request. Preparation of a request may be
+ * performed while another request is running on the host.
+ */
+void mmc_pre_req(struct mmc_host *host, struct mmc_request *mrq,
+ bool is_first_req)
+{
+ if (host->ops->pre_req)
+ host->ops->pre_req(host, mrq, is_first_req);
+}
+EXPORT_SYMBOL(mmc_pre_req);
+
+/**
+ * mmc_post_req - Post process a completed request
+ * @host: MMC host to post process command
+ * @mrq: MMC request to post process for
+ * @err: Error, if none zero, clean up any resources made in pre_req
+ *
+ * Let the host post process a completed request. Post processing of
+ * a request may be performed while another reuqest is running.
+ */
+void mmc_post_req(struct mmc_host *host, struct mmc_request *mrq, int err)
+{
+ if (host->ops->post_req)
+ host->ops->post_req(host, mrq, err);
+}
+EXPORT_SYMBOL(mmc_post_req);
+
+/**
+ * mmc_start_req - start a request
* @host: MMC host to start command
* @mrq: MMC request to start
*
- * Start a new MMC custom command request for a host, and wait
- * for the command to complete. Does not attempt to parse the
- * response.
+ * Start a new MMC custom command request for a host.
+ * Does not wait for the command to complete.
*/
-void mmc_wait_for_req(struct mmc_host *host, struct mmc_request *mrq)
+void mmc_start_req(struct mmc_host *host, struct mmc_request *mrq)
{
- DECLARE_COMPLETION_ONSTACK(complete);
-
- mrq->done_data = &complete;
+ init_completion(&mrq->completion);
mrq->done = mmc_wait_done;
mmc_start_request(host, mrq);
+}
+EXPORT_SYMBOL(mmc_start_req);
- wait_for_completion(&complete);
+/**
+ * mmc_wait_for_req_done - wait for completion of request
+ * @mrq: MMC request to wait for
+ *
+ * Wait for the command to complete. Does not attempt to parse the
+ * response.
+ */
+void mmc_wait_for_req_done(struct mmc_request *mrq)
+{
+ wait_for_completion(&mrq->completion);
}
+EXPORT_SYMBOL(mmc_wait_for_req_done);
+/**
+ * mmc_wait_for_req - start a request and wait for completion
+ * @host: MMC host to start command
+ * @mrq: MMC request to start
+ *
+ * Start a new MMC custom command request for a host, and wait
+ * for the command to complete. Does not attempt to parse the
+ * response.
+ */
+void mmc_wait_for_req(struct mmc_host *host, struct mmc_request *mrq)
+{
+ mmc_start_req(host, mrq);
+ mmc_wait_for_req_done(mrq);
+}
EXPORT_SYMBOL(mmc_wait_for_req);
/**
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 07f27af..5bbfb71 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -117,6 +117,7 @@ struct mmc_data {
unsigned int sg_len; /* size of scatter list */
struct scatterlist *sg; /* I/O scatter list */
+ s32 host_cookie; /* host private data */
};
struct mmc_request {
@@ -124,13 +125,19 @@ struct mmc_request {
struct mmc_data *data;
struct mmc_command *stop;
- void *done_data; /* completion data */
+ struct completion completion;
void (*done)(struct mmc_request *);/* completion
function */
};
struct mmc_host;
struct mmc_card;
+extern void mmc_pre_req(struct mmc_host *host, struct mmc_request *mrq,
+ bool is_first_req);
+extern void mmc_post_req(struct mmc_host *host, struct mmc_request *mrq,
+ int err);
+extern void mmc_start_req(struct mmc_host *host, struct mmc_request *mrq);
+extern void mmc_wait_for_req_done(struct mmc_request *mrq);
extern void mmc_wait_for_req(struct mmc_host *, struct mmc_request *);
extern int mmc_wait_for_cmd(struct mmc_host *, struct mmc_command *, int);
extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index bcb793e..c056a3d 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -88,6 +88,15 @@ struct mmc_host_ops {
*/
int (*enable)(struct mmc_host *host);
int (*disable)(struct mmc_host *host, int lazy);
+ /*
+ * It is optional for the host to implement pre_req and post_req in
+ * order to support double buffering of requests (prepare one
+ * request while another request is active).
+ */
+ void (*post_req)(struct mmc_host *host, struct mmc_request *req,
+ int err);
+ void (*pre_req)(struct mmc_host *host, struct mmc_request *req,
+ bool is_first_req);
void (*request)(struct mmc_host *host, struct mmc_request *req);
/*
* Avoid calling these three functions too often or in a "fast path",
--
1.7.4.1
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