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SubjectRe: [PATCH 02/17] fpga: dfl: fme: align PR buffer size per PR datawidth
On Mon, Mar 25, 2019 at 12:50:40PM -0500, Alan Tull wrote:
> 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?
>

Hi Alan,

Thanks for the review, acutally per spec, hw doesn't care about the
extra padding data. So for now, i guess we don't need this.

Thanks
Hao

> Alan
>

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