* [PATCH] ufs: adjust queue settings to PRDT limitations
@ 2013-09-21 6:36 Akinobu Mita
2013-09-23 7:48 ` Subhash Jadavani
0 siblings, 1 reply; 3+ messages in thread
From: Akinobu Mita @ 2013-09-21 6:36 UTC (permalink / raw)
To: linux-scsi
Cc: Akinobu Mita, Vinayak Holikatti, Santosh Y, James E.J. Bottomley
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>
Cc: Vinayak Holikatti <vinholikatti@gmail.com>
Cc: Santosh Y <santoshsy@gmail.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: linux-scsi@vger.kernel.org
---
drivers/scsi/ufs/ufshcd.c | 15 +++++++++++++++
drivers/scsi/ufs/ufshci.h | 3 +++
2 files changed, 18 insertions(+)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 7ef9c17..c60537f 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1919,6 +1919,20 @@ static int ufshcd_slave_alloc(struct scsi_device *sdev)
}
/**
+ * 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
*/
@@ -2749,6 +2763,7 @@ 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,
.eh_abort_handler = ufshcd_abort,
.eh_device_reset_handler = ufshcd_device_reset,
diff --git a/drivers/scsi/ufs/ufshci.h b/drivers/scsi/ufs/ufshci.h
index 0475c66..c8de354 100644
--- a/drivers/scsi/ufs/ufshci.h
+++ b/drivers/scsi/ufs/ufshci.h
@@ -296,6 +296,9 @@ enum {
MASK_OCS = 0x0F,
};
+#define PRDT_DATA_BYTE_COUNT_MAX (256 * 1024)
+#define PRDT_DATA_BYTE_COUNT_PAD 4
+
/**
* struct ufshcd_sg_entry - UFSHCI PRD Entry
* @base_addr: Lower 32bit physical address DW-0
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] ufs: adjust queue settings to PRDT limitations
2013-09-21 6:36 [PATCH] ufs: adjust queue settings to PRDT limitations Akinobu Mita
@ 2013-09-23 7:48 ` Subhash Jadavani
2013-09-23 22:42 ` Akinobu Mita
0 siblings, 1 reply; 3+ messages in thread
From: Subhash Jadavani @ 2013-09-23 7:48 UTC (permalink / raw)
To: Akinobu Mita
Cc: linux-scsi, Vinayak Holikatti, Santosh Y, James E.J. Bottomley
On 9/21/2013 12:06 PM, Akinobu Mita wrote:
> 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>
> Cc: Vinayak Holikatti <vinholikatti@gmail.com>
> Cc: Santosh Y <santoshsy@gmail.com>
> Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
> Cc: linux-scsi@vger.kernel.org
> ---
> drivers/scsi/ufs/ufshcd.c | 15 +++++++++++++++
> drivers/scsi/ufs/ufshci.h | 3 +++
> 2 files changed, 18 insertions(+)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 7ef9c17..c60537f 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1919,6 +1919,20 @@ static int ufshcd_slave_alloc(struct scsi_device *sdev)
> }
>
> /**
> + * 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
> */
> @@ -2749,6 +2763,7 @@ 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,
> .eh_abort_handler = ufshcd_abort,
> .eh_device_reset_handler = ufshcd_device_reset,
> diff --git a/drivers/scsi/ufs/ufshci.h b/drivers/scsi/ufs/ufshci.h
> index 0475c66..c8de354 100644
> --- a/drivers/scsi/ufs/ufshci.h
> +++ b/drivers/scsi/ufs/ufshci.h
> @@ -296,6 +296,9 @@ enum {
> MASK_OCS = 0x0F,
> };
>
Ideally there should be comment here to explain the reason for this
limitation. I see comments in commit text but not here in code.
Its not general practice to browse through history to understand the
reason behind this limitations. so it always helps to add comments in
code itself.
Regards,
Subhash
> +#define PRDT_DATA_BYTE_COUNT_MAX (256 * 1024)
> +#define PRDT_DATA_BYTE_COUNT_PAD 4
> +
> /**
> * struct ufshcd_sg_entry - UFSHCI PRD Entry
> * @base_addr: Lower 32bit physical address DW-0
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] ufs: adjust queue settings to PRDT limitations
2013-09-23 7:48 ` Subhash Jadavani
@ 2013-09-23 22:42 ` Akinobu Mita
0 siblings, 0 replies; 3+ messages in thread
From: Akinobu Mita @ 2013-09-23 22:42 UTC (permalink / raw)
To: Subhash Jadavani
Cc: linux-scsi, Vinayak Holikatti, Santosh Y, James E.J. Bottomley
> Ideally there should be comment here to explain the reason for this limitation. I see comments in commit text but not here in code.
> Its not general practice to browse through history to understand the reason behind this limitations. so it always helps to add comments in code itself.
OK, I'll update the patch with the comment.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-09-23 22:46 UTC | newest]
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2013-09-21 6:36 [PATCH] ufs: adjust queue settings to PRDT limitations Akinobu Mita
2013-09-23 7:48 ` Subhash Jadavani
2013-09-23 22:42 ` Akinobu Mita
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