lkml.org 
[lkml]   [2018]   [Oct]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v9 6/9] i3c: master: Add driver for Cadence IP
On Thu, 25 Oct 2018 17:30:26 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On 10/24/18, Boris Brezillon <boris.brezillon@bootlin.com> wrote:
> > Hi Arnd,
> >
> > On Mon, 22 Oct 2018 15:34:01 +0200
> > Boris Brezillon <boris.brezillon@bootlin.com> wrote:
> >
> >
> >> +
> >> +static void cdns_i3c_master_rd_from_rx_fifo(struct cdns_i3c_master
> >> *master,
> >> + u8 *bytes, int nbytes)
> >> +{
> >> + readsl(master->regs + RX_FIFO, bytes, nbytes / 4);
> >
> > Vitor reported a problem with readsl(): this function expects the 2nd
> > argument to be aligned on 32-bit, which is not guaranteed here. Unless
> > you see a better solution, I'll switch back to a loop doing:
> >
> > for (i = 0; i < nbytes; i += 4) {
> > u32 tmp = __raw_readl(...);
> > memcpy(bytes + i, &tmp,
> > nbytes - i > 4 ? 4 : nbytes - i);
> > }
>
> Could we maybe mandate that the buffer itself must be aligned here?
> What would be a reason why we see an unaligned target buffer?

Well, the buffers we pass to i3c_send_ccc_cmd() are not necessarily
aligned because they're not dynamically allocated (allocated on the
stack) and are not naturally aligned on 32-bits (either because they
are smaller than 32bits or because the struct is declared __packed).

I guess I could dynamically allocate the payload, but that requires
going over all users of i3c_send_ccc_cmd() to patch them.

\
 
 \ /
  Last update: 2018-10-25 18:08    [W:0.096 / U:1.568 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site