On Wed, Feb 14, 2018 at 03:51:31PM +0100, Benjamin Tissoires wrote:
> On Tue, Feb 13, 2018 at 1:03 PM, Rodrigo Rivas Costa
> > +#define STEAM_FEATURE_REPORT_SIZE 65
> > +
> > +static int steam_send_report(struct steam_device *steam,
> > + u8 *cmd, int size)
> > +{
> > + int retry;
> > + int ret;
> > + u8 *buf = kzalloc(STEAM_FEATURE_REPORT_SIZE, GFP_KERNEL);
>
> Please use hid_alloc_report_buf() as sometimes we need to allocate a
> slightly bigger report.
I have an issue with this one. The problem is that using
hid_report_len() on the feature report returns 64. But I must call
hid_hw_raw_request() with 65 or it will fail with EOVERFLOW.
Currently I'm allocating a buffer of 65 bytes and all is well.
If I change to hid_alloc_report_buf(), the current implementation
allocates (64+7), so I'm still safe. But I'm worried that the extra
bytes are not guaranteed and a future implementation could return
exactly 64 bytes, leaving me 1 byte short.
About why an array of 65 is required for a report of size 64, I think it
is related to hid_report->id == 0 (so hid_report_enum->numbered == 0).
So what would be the proper solution?
Thanks.
Rodrigo.
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