ufs: adjust queue settings to PRDT limitations

The data byte count field of PRDT indicates the length of data block
which is a segment of data transfer for SCSI commands.  The value of
this field shall have Dword granularity and the the maximum of length
is 256KB.

This adjusts dma pad mask and max segment size to the above-mentioned
PRDT limitations.

Signed-off-by: Akinobu Mita <mita@fixstars.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Tested-by: Dolev Raviv <draviv@codeaurora.org>
Acked-by: Vinayak Holikatti <vinholikatti@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index f189e8a6cb1e6f36363c20a1ad2c29da9b82ef42..af1bffc1eac8a86a419e1494b19364b2cbf29007 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -2042,6 +2042,20 @@ int ufshcd_change_queue_depth(struct scsi_device *sdev, int depth, int reason)
        return depth;
 }
 
+/**
+ * ufshcd_slave_configure - adjust SCSI device configurations
+ * @sdev: pointer to SCSI device
+ */
+static int ufshcd_slave_configure(struct scsi_device *sdev)
+{
+       struct request_queue *q = sdev->request_queue;
+
+       blk_queue_update_dma_pad(q, PRDT_DATA_BYTE_COUNT_PAD - 1);
+       blk_queue_max_segment_size(q, PRDT_DATA_BYTE_COUNT_MAX);
+
+       return 0;
+}
+
 /**
  * ufshcd_slave_destroy - remove SCSI device configurations
  * @sdev: pointer to SCSI device
@@ -3145,6 +3159,7 @@ static struct scsi_host_template ufshcd_driver_template = {
        .proc_name              = UFSHCD,
        .queuecommand           = ufshcd_queuecommand,
        .slave_alloc            = ufshcd_slave_alloc,
+       .slave_configure        = ufshcd_slave_configure,
        .slave_destroy          = ufshcd_slave_destroy,
        .change_queue_depth     = ufshcd_change_queue_depth,
        .eh_abort_handler       = ufshcd_abort,

diff --git a/drivers/scsi/ufs/ufshci.h b/drivers/scsi/ufs/ufshci.h
index 9abc7e32b43d93350a710f757f651ad3a586248e..e1b844bc94607b302ff70100729b9fa83d7ae5fc 100644 (file)
--- a/drivers/scsi/ufs/ufshci.h
+++ b/drivers/scsi/ufs/ufshci.h
@@ -296,6 +296,11 @@ enum {
        MASK_OCS                        = 0x0F,
 };
 
+/* The maximum length of the data byte count field in the PRDT is 256KB */
+#define PRDT_DATA_BYTE_COUNT_MAX       (256 * 1024)
+/* The granularity of the data byte count field in the PRDT is 32-bit */
+#define PRDT_DATA_BYTE_COUNT_PAD       4
+
 /**
  * struct ufshcd_sg_entry - UFSHCI PRD Entry
  * @base_addr: Lower 32bit physical address DW-0