[U-Boot] [PATCH v2] common: usb_storage : Implement logic to calculate optimal usb maximum trasfer blocks

[Marek Vasut <marex@denx.de>]

On 06/06/2016 06:19 AM, Rajesh Bhagat wrote:
> 
> 
>> -----Original Message-----
>> From: Marek Vasut [mailto:marex at denx.de]
>> Sent: Saturday, June 04, 2016 4:22 AM
>> To: Rajesh Bhagat <rajesh.bhagat@nxp.com>; u-boot at lists.denx.de
>> Cc: sjg at chromium.org; york sun <york.sun@nxp.com>; Sriram Dash
>> <sriram.dash@nxp.com>
>> Subject: Re: [PATCH v2] common: usb_storage : Implement logic to calculate optimal
>> usb maximum trasfer blocks
>>
>> On 06/02/2016 06:56 AM, Rajesh Bhagat wrote:
>>> 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>
>>> ---
>>>  common/usb_storage.c | 71
>>> +++++++++++++++++++++++++++++++++++++++++++---------
>>>  1 file changed, 59 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/common/usb_storage.c b/common/usb_storage.c index
>>> 7e6e52d..eee8f4c 100644
>>> --- a/common/usb_storage.c
>>> +++ b/common/usb_storage.c
>>> @@ -106,10 +106,13 @@ struct us_data {
>>>   * enough free heap space left, but the SCSI READ(10) and WRITE(10) commands
>> are
>>>   * limited to 65535 blocks.
>>>   */
>>> +#define USB_MIN_XFER_BLK	4095
>>>  #define USB_MAX_XFER_BLK	65535
>>>  #else
>>> +#define USB_MIN_XFER_BLK	20
>>>  #define USB_MAX_XFER_BLK	20
>>>  #endif
>>> +#define USB_CUR_XFER_BLK(n)	(n >= 0 ? ((1 << (12 + (n))) - 1) : 0)
>>
> 
> Hello Marek, 
> 
>> Can this be ever called with n < 0 ? You should make this into a function to get
>> typechecking on it too.
>>
> 
> Yes. When transfer fails for the first time (pos - 1) is passed to this macro. Ok, 
> I will convert it to a function in v3.

This should be handled outside of the macro then.

>>>  #ifndef CONFIG_BLK
>>>  static struct us_data usb_stor[USB_MAX_STOR_DEV]; @@ -1117,11
>>> +1120,13 @@ static unsigned long usb_stor_read(struct blk_desc *block_dev,
>> lbaint_t blknr,
>>>  	unsigned short smallblks;
>>>  	struct usb_device *udev;
>>>  	struct us_data *ss;
>>> -	int retry;
>>> +	int retry, pos = 0;
>>> +	bool retry_flag = false;
>>>  	ccb *srb = &usb_ccb;
>>>  #ifdef CONFIG_BLK
>>>  	struct blk_desc *block_dev;
>>>  #endif
>>> +	unsigned short usb_cur_xfer_blk = USB_CUR_XFER_BLK(pos);
>>
>> How will this behave if you keep alternating between two block_dev devices ? It will
>> always start looking for the best possible transfer length from scratch, right ? That's
>> not great ...
> 
> How about adding a field name "cur_xfer_blks" in struct usb_device and updating it 
> on device basis , it will help retain the value.

That might work, yes.

> struct usb_device {
> ...
>         unsigned short cur_xfer_blks;
> };
>   
>>
>>>  	if (blkcnt == 0)
>>>  		return 0;
>>> @@ -1153,26 +1158,46 @@ static unsigned long usb_stor_read(struct blk_desc
>> *block_dev, lbaint_t blknr,
>>>  		/* XXX need some comment here */
>>>  		retry = 2;
>>>  		srb->pdata = (unsigned char *)buf_addr;
>>> -		if (blks > USB_MAX_XFER_BLK)
>>> -			smallblks = USB_MAX_XFER_BLK;
>>> +		if (blks > usb_cur_xfer_blk)
>>> +			smallblks = usb_cur_xfer_blk;
>>>  		else
>>>  			smallblks = (unsigned short) blks;
>>>  retry_it:
>>> -		if (smallblks == USB_MAX_XFER_BLK)
>>> +		debug("usb_read: retry #%d, usb_cur_xfer_blk %hu, smallblks %hu\n",
>>> +		      retry, usb_cur_xfer_blk, smallblks);
>>> +		if (smallblks == usb_cur_xfer_blk)
>>>  			usb_show_progress();
>>>  		srb->datalen = block_dev->blksz * smallblks;
>>>  		srb->pdata = (unsigned char *)buf_addr;
>>>  		if (usb_read_10(srb, ss, start, smallblks)) {
>>>  			debug("Read ERROR\n");
>>>  			usb_request_sense(srb, ss);
>>> -			if (retry--)
>>> +			if (retry--) {
>>> +				/* decrease the usb_cur_xfer_blk */
>>> +				unsigned short size = USB_CUR_XFER_BLK(pos - 1);
>>> +				if (size >= USB_MIN_XFER_BLK) {
>>> +					smallblks = size;
>>> +					usb_cur_xfer_blk = smallblks;
>>> +					pos--;
>>> +				}
>>> +				retry_flag = true;
>>>  				goto retry_it;
>>
>> What is the reason for having the same code twice in this patch ? Just pull the identical
>> stuff into a function.
>>
> 
> Ok, I will add above code in function namely dec_cur_xfer_blks/ inc_cur_xfer_blks in v3.
> 
> Best Regards,
> Rajesh Bhagat 
> 
>>> +			}
>>>  			blkcnt -= blks;
>>>  			break;
>>>  		}
>>>  		start += smallblks;
>>>  		blks -= smallblks;
>>>  		buf_addr += srb->datalen;
>>> +
>>> +		/* try to increase the usb_cur_xfer_blk */
>>> +		if (!retry_flag) {
>>> +			unsigned short size = USB_CUR_XFER_BLK(pos + 1);
>>> +			if (size <= blks && size <= USB_MAX_XFER_BLK) {
>>> +				usb_cur_xfer_blk = size;
>>> +				pos++;
>>> +			}
>>> +		}
>>>  	} while (blks != 0);
>>>  	ss->flags &= ~USB_READY;
>>>
>>> @@ -1181,7 +1206,7 @@ retry_it:
>>>  	      start, smallblks, buf_addr);
>>>
>>>  	usb_disable_asynch(0); /* asynch transfer allowed */
>>> -	if (blkcnt >= USB_MAX_XFER_BLK)
>>> +	if (blkcnt >= usb_cur_xfer_blk)
>>>  		debug("\n");
>>>  	return blkcnt;
>>>  }
>>> @@ -1199,11 +1224,13 @@ static unsigned long usb_stor_write(struct blk_desc
>> *block_dev, lbaint_t blknr,
>>>  	unsigned short smallblks;
>>>  	struct usb_device *udev;
>>>  	struct us_data *ss;
>>> -	int retry;
>>> +	int retry, pos = 0;
>>> +	bool retry_flag = false;
>>>  	ccb *srb = &usb_ccb;
>>>  #ifdef CONFIG_BLK
>>>  	struct blk_desc *block_dev;
>>>  #endif
>>> +	unsigned short usb_cur_xfer_blk = USB_CUR_XFER_BLK(pos);
>>>
>>>  	if (blkcnt == 0)
>>>  		return 0;
>>> @@ -1239,26 +1266,46 @@ static unsigned long usb_stor_write(struct blk_desc
>> *block_dev, lbaint_t blknr,
>>>  		 */
>>>  		retry = 2;
>>>  		srb->pdata = (unsigned char *)buf_addr;
>>> -		if (blks > USB_MAX_XFER_BLK)
>>> -			smallblks = USB_MAX_XFER_BLK;
>>> +		if (blks > usb_cur_xfer_blk)
>>> +			smallblks = usb_cur_xfer_blk;
>>>  		else
>>>  			smallblks = (unsigned short) blks;
>>>  retry_it:
>>> -		if (smallblks == USB_MAX_XFER_BLK)
>>> +		debug("usb_write: retry #%d, usb_cur_xfer_blk %hu, smallblks %hu\n",
>>> +		      retry, usb_cur_xfer_blk, smallblks);
>>> +		if (smallblks == usb_cur_xfer_blk)
>>>  			usb_show_progress();
>>>  		srb->datalen = block_dev->blksz * smallblks;
>>>  		srb->pdata = (unsigned char *)buf_addr;
>>>  		if (usb_write_10(srb, ss, start, smallblks)) {
>>>  			debug("Write ERROR\n");
>>>  			usb_request_sense(srb, ss);
>>> -			if (retry--)
>>> +			if (retry--) {
>>> +				/* decrease the usb_cur_xfer_blk */
>>> +				unsigned short size = USB_CUR_XFER_BLK(pos - 1);
>>> +				if (size >= USB_MIN_XFER_BLK) {
>>> +					smallblks = size;
>>> +					usb_cur_xfer_blk = smallblks;
>>> +					pos--;
>>> +				}
>>> +				retry_flag = true;
>>>  				goto retry_it;
>>> +			}
>>>  			blkcnt -= blks;
>>>  			break;
>>>  		}
>>>  		start += smallblks;
>>>  		blks -= smallblks;
>>>  		buf_addr += srb->datalen;
>>> +
>>> +		/* try to increase the usb_cur_xfer_blk */
>>> +		if (!retry_flag) {
>>> +			unsigned short size = USB_CUR_XFER_BLK(pos + 1);
>>> +			if (size <= blks && size <= USB_MAX_XFER_BLK) {
>>> +				usb_cur_xfer_blk = size;
>>> +				pos++;
>>> +			}
>>> +		}
>>>  	} while (blks != 0);
>>>  	ss->flags &= ~USB_READY;
>>>
>>> @@ -1266,7 +1313,7 @@ retry_it:
>>>  	      PRIxPTR "\n", start, smallblks, buf_addr);
>>>
>>>  	usb_disable_asynch(0); /* asynch transfer allowed */
>>> -	if (blkcnt >= USB_MAX_XFER_BLK)
>>> +	if (blkcnt >= usb_cur_xfer_blk)
>>>  		debug("\n");
>>>  	return blkcnt;
>>>
>>>
>>
>>
>> --
>> Best regards,
>> Marek Vasut


-- 
Best regards,
Marek Vasut