RE: [PATCH v2] ufs: adjust queue settings to PRDT limitations

["Dolev Raviv" <draviv@codeaurora.org>]

Hi,
I couldn't find this patch in scsi-misc branch. Was it merged somewhere
else?

Thanks,
Dolev
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-----Original Message-----
From: linux-scsi-owner@vger.kernel.org
[mailto:linux-scsi-owner@vger.kernel.org] On Behalf Of vinayak holikatti
Sent: Friday, October 11, 2013 8:05 AM
To: Akinobu Mita
Cc: linux-scsi@vger.kernel.org; Subhash Jadavani; Santosh Y; James E.J.
Bottomley
Subject: Re: [PATCH v2] ufs: adjust queue settings to PRDT limitations

On Wed, Sep 25, 2013 at 7:17 PM, Akinobu Mita <mita@fixstars.com> 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: Subhash Jadavani <subhashj@codeaurora.org>
> 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
> ---
> * Change from v1
> - Add comments for PRDT limitations as suggested by Subhash Jadavani
>
>  drivers/scsi/ufs/ufshcd.c | 15 +++++++++++++++  
> drivers/scsi/ufs/ufshci.h |  5 +++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c 
> index a2abe9a..660792e 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1918,6 +1918,20 @@ 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
>   */
> @@ -2748,6 +2762,7 @@ 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..b2b7004 100644
> --- 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

Acked-by: Vinayak Holikatti <vinholikatti@gmail.com>
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