On 9 June 2016 at 00:32, Rajesh Bhagat rajesh.bhagat@nxp.com wrote:
From: Rajesh Bhagat rajesh.bhagat@freescale.com
Implements the logic to calculate the optimal usb maximum trasfer blocks instead of sending USB_MAX_XFER_BLK blocks which is 65535 and 20 in case of EHCI and other USB protocols respectively.
It defines USB_MIN_XFER_BLK/USB_MAX_XFER_BLK trasfer blocks that should be checked for success starting from minimum to maximum, and rest of the read/write are performed with that optimal value. It tries to increase/ decrease the blocks in follwing scenarios:
1.decrease blocks: when read/write for a particular number of blocks fails. 2. increase blocks: when read/write for a particular number of blocks pass and amount left to trasfer is greater than current number of blocks.
Currently changes are done for EHCI where min = 4096 and max = 65535 is taken. And for other cases code is left unchanged by keeping min = max = 20.
Signed-off-by: Sriram Dash sriram.dash@nxp.com Signed-off-by: Rajesh Bhagat rajesh.bhagat@nxp.com
Changes in v4:
- Adds udev paramater in dec/inc_cur_xfer_blks function and adds sanity check on it.
- Changes type of pos varible to unsigned int in dec/inc_cur_xfer_blks
- Removes usage of pos varible from usb_stor_read/write
Changes in v3:
- Adds cur_xfer_blks in struct usb_device to retain values
- Adds functions dec/inc_cur_xfer_blks to remove code duplication
- Moves check from macro to calling functions
Changes in v2:
- Removes table to store blocks and use formula (1 << (12 + n)) - 1
- Adds logic to start from minimum, go to maximum in each read/write
common/usb_storage.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++---- include/usb.h | 1 + 2 files changed, 64 insertions(+), 5 deletions(-)
Reviewed-by: Simon Glass sjg@chromium.org
I'm not keen on the 'unsigned short' for the size. Perhaps add a comment to your 65535 #define that it cannot go higher?