scsi: ufs: core: Increase the maximum data buffer size

Measurements for one particular UFS controller + UFS device show a 25%
higher read bandwidth if the maximum data buffer size is increased from 512
KiB to 1 MiB. Hence increase the maximum size of the data buffer associated
with a single request from SCSI_DEFAULT_MAX_SECTORS (1024) * 512 bytes =
512 KiB to 1 MiB.

Notes:

 - The maximum data buffer size supported by the UFSHCI specification
   is 65535 * 256 KiB or about 16 GiB.

 - The maximum data buffer size for READ(10) commands is 65535 logical
   blocks. To transfer more than 65535 * 4096 bytes = 255 MiB with a single
   SCSI command, the READ(16) command is required. Support for READ(16) is
   optional in the UFS 3.1 and UFS 4.0 standards.

Link: https://lore.kernel.org/r/[email protected]
Cc: Adrian Hunter <[email protected]>
Cc: Avri Altman <[email protected]>
Cc: Bean Huo <[email protected]>
Cc: Stanley Chu <[email protected]>
Tested-by: Avri Altman <[email protected]>
Acked-by: Avri Altman <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: bvanassche

drivers/ufs/core/ufshcd.c

@@ -8304,6 +8304,7 @@ static struct scsi_host_template ufshcd_driver_template = {
 	.cmd_per_lun		= UFSHCD_CMD_PER_LUN,
 	.can_queue		= UFSHCD_CAN_QUEUE,
 	.max_segment_size	= PRDT_DATA_BYTE_COUNT_MAX,
+	.max_sectors		= (1 << 20) / SECTOR_SIZE, /* 1 MiB */
 	.max_host_blocked	= 1,
 	.track_queue_depth	= 1,
 	.sdev_groups		= ufshcd_driver_groups,