Re: [PATCH 2/2] ieee1934: dv1394 interrupt enabling/disabling broken on big-endian

Stefan Richter
2008-12-14T00:41:19Z

For linux1394-devel to know:

Harvey Harrison wrote at LKML:
> After annotating the frame structs, this was left:
> drivers/ieee1394/dv1394.c:2113:23: warning: invalid assignment: |=
> drivers/ieee1394/dv1394.c:2113:23: left side has type restricted __le32
> drivers/ieee1394/dv1394.c:2113:23: right side has type int
> drivers/ieee1394/dv1394.c:2121:24: warning: invalid assignment: &=
> drivers/ieee1394/dv1394.c:2121:24: left side has type restricted __le32
> drivers/ieee1394/dv1394.c:2121:24: right side has type int
> drivers/ieee1394/dv1394.c:2123:24: warning: invalid assignment: |=
> drivers/ieee1394/dv1394.c:2123:24: left side has type restricted __le32
> drivers/ieee1394/dv1394.c:2123:24: right side has type int
>
> Which looks like a real bug on a big-endian arch as it would set/clear
> the wrong bit.
>
> Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
> ---
> drivers/ieee1394/dv1394.c | 8 ++++----
> 1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/ieee1394/dv1394.c b/drivers/ieee1394/dv1394.c
> index f258e61..a329e6b 100644
> --- a/drivers/ieee1394/dv1394.c
> +++ b/drivers/ieee1394/dv1394.c
> @@ -2110,17 +2110,17 @@ static void ir_tasklet_func(unsigned long data)
> f = video->frames[next_i / MAX_PACKETS];
> next = &(f->descriptor_pool[next_i % MAX_PACKETS]);
> next_dma = ((unsigned long) block - (unsigned long) f->descriptor_pool) + f->descriptor_pool_dma;
> - next->u.in.il.q[0] |= 3 << 20; /* enable interrupt */
> - next->u.in.il.q[2] = 0; /* disable branch */
> + next->u.in.il.q[0] |= cpu_to_le32(3 << 20); /* enable interrupt */
> + next->u.in.il.q[2] = cpu_to_le32(0); /* disable branch */
>
> /* link previous to next */
> prev_i = (next_i == 0) ? (MAX_PACKETS * video->n_frames - 1) : (next_i - 1);
> f = video->frames[prev_i / MAX_PACKETS];
> prev = &(f->descriptor_pool[prev_i % MAX_PACKETS]);
> if (prev_i % (MAX_PACKETS/2)) {
> - prev->u.in.il.q[0] &= ~(3 << 20); /* no interrupt */
> + prev->u.in.il.q[0] &= ~cpu_to_le32(3 << 20); /* no interrupt */
> } else {
> - prev->u.in.il.q[0] |= 3 << 20; /* enable interrupt */
> + prev->u.in.il.q[0] |= cpu_to_le32(3 << 20); /* enable interrupt */
> }
> prev->u.in.il.q[2] = cpu_to_le32(next_dma | 1); /* set Z=1 */
> wmb();

Looks like a bug + correct fix indeed. Apparently dv1394 was never used on big
endian PCs. Which is good, because we want to phase out dv1394 eventually.
--
Stefan Richter
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