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SubjectRe: [PATCH 02/17] fpga: dfl: fme: align PR buffer size per PR datawidth
On Sun, Mar 24, 2019 at 10:23 PM Wu Hao <hao.wu@intel.com> wrote:

Hi Hao,

Looks good, one question below.

>
> Current driver checks if input bitstream file size is aligned or
> not per PR data width (default 32bits). It requires one additional
> step for end user when they generate the bitstream file, padding
> extra zeros to bitstream file to align its size per PR data width,
> but they don't have to as hardware will drop extra padding bytes
> automatically.
>
> In order to simplify the user steps, this patch aligns PR buffer
> size per PR data width in driver, to allow user to pass unaligned
> size bitstream files to driver.
>
> Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> Signed-off-by: Wu Hao <hao.wu@intel.com>
> ---
> drivers/fpga/dfl-fme-pr.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/fpga/dfl-fme-pr.c b/drivers/fpga/dfl-fme-pr.c
> index d9ca955..c1fb1fe 100644
> --- a/drivers/fpga/dfl-fme-pr.c
> +++ b/drivers/fpga/dfl-fme-pr.c
> @@ -74,6 +74,7 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
> struct dfl_fme *fme;
> unsigned long minsz;
> void *buf = NULL;
> + size_t length;
> int ret = 0;
> u64 v;
>
> @@ -85,9 +86,6 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
> if (port_pr.argsz < minsz || port_pr.flags)
> return -EINVAL;
>
> - if (!IS_ALIGNED(port_pr.buffer_size, 4))
> - return -EINVAL;
> -
> /* get fme header region */
> fme_hdr = dfl_get_feature_ioaddr_by_id(&pdev->dev,
> FME_FEATURE_ID_HEADER);
> @@ -103,7 +101,13 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
> port_pr.buffer_size))
> return -EFAULT;
>
> - buf = vmalloc(port_pr.buffer_size);
> + /*
> + * align PR buffer per PR bandwidth, as HW ignores the extra padding
> + * data automatically.
> + */
> + length = ALIGN(port_pr.buffer_size, 4);
> +
> + buf = vmalloc(length);

Since it may not be completely filled, would it be worthwhile to alloc
a zero'ed buff?

Alan

> if (!buf)
> return -ENOMEM;
>
> @@ -140,7 +144,7 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
> fpga_image_info_free(region->info);
>
> info->buf = buf;
> - info->count = port_pr.buffer_size;
> + info->count = length;
> info->region_id = port_pr.port_id;
> region->info = info;
>
> --
> 2.7.4
>

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