[RESEND PATCH v4 8/8] bus: mhi: Improve documentation on channel transfer setup APIs

Bhaumik Bhatt
2021-01-08T20:42:01Z

The mhi_prepare_for_transfer() and mhi_unprepare_from_transfer()
APIs could use better explanation, especially with the addition
of two new APIs to start and stop the transfers on channels. Add
better set of information for those APIs.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: Hemant Kumar <hemantk@codeaurora.org>
---
include/linux/mhi.h | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index b5e11ba..94c5075 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -703,13 +703,35 @@ int mhi_device_get_sync(struct mhi_device *mhi_dev);
void mhi_device_put(struct mhi_device *mhi_dev);

/**
- * mhi_prepare_for_transfer - Setup channel for data transfer
+ * mhi_prepare_for_transfer - Setup UL and DL channels for data transfer.
+ * Allocate and initialize the channel context and
+ * also issue the START channel command to both
+ * channels. Channels can be started only if both
+ * host and device execution environments match and
+ * channels are in a DISABLED state. Calling the
+ * mhi_start_transfer() function is not required
+ * afterwards as channels are already started. This
+ * function also initializes the channel context
+ * whereas mhi_start_transfer() can only be used to
+ * issue the start channel command once the context
+ * is setup.
* @mhi_dev: Device associated with the channels
*/
int mhi_prepare_for_transfer(struct mhi_device *mhi_dev);

/**
- * mhi_unprepare_from_transfer - Unprepare the channels
+ * mhi_unprepare_from_transfer - Reset UL and DL channels for data transfer.
+ * Issue the RESET channel command and let the
+ * device clean-up the context so no incoming
+ * transfers are seen on the host. Free memory
+ * associated with the context on host. If device
+ * is unresponsive, only perform a host side
+ * clean-up. Channels can be reset only if both
+ * host and device execution environments match
+ * and channels are in an ENABLED, STOPPED or
+ * SUSPENDED state. Calling mhi_stop_transfer() is
+ * not required before calling this function as it
+ * will only stop transfers, not reset channels.
* @mhi_dev: Device associated with the channels
*/
void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev);