Re: [PATCH] gpu: host1x: handle the correct # of syncpt regs

[Thierry Reding]

On Thu, Apr 03, 2014 at 11:09:22AM +0300, Terje Bergström wrote:
> On 01.04.2014 23:10, Stephen Warren wrote:
> > diff --git a/drivers/gpu/host1x/hw/intr_hw.c 
> > b/drivers/gpu/host1x/hw/intr_hw.c
> > index db9017adfe2b..17407b2de2bf 100644
> > --- a/drivers/gpu/host1x/hw/intr_hw.c
> > +++ b/drivers/gpu/host1x/hw/intr_hw.c
> > @@ -47,7 +47,7 @@ static irqreturn_t syncpt_thresh_isr(int irq, void 
> > *dev_id)
> >     unsigned long reg;
> >     int i, id;
> >  
> > -   for (i = 0; i <= BIT_WORD(host->info->nb_pts); i++) {
> > +   for (i = 0; i < BITS_TO_LONGS(host->info->nb_pts); i++) {
> >             reg = host1x_sync_readl(host,
> >                     HOST1X_SYNC_SYNCPT_THRESH_CPU0_INT_STATUS(i));
> >             for_each_set_bit(id, &reg, BITS_PER_LONG) {
> > @@ -64,7 +64,7 @@ static void _host1x_intr_disable_all_syncpt_intrs(struct 
> > host1x *host)
> >  {
> >     u32 i;
> >  
> > -   for (i = 0; i <= BIT_WORD(host->info->nb_pts); ++i) {
> > +   for (i = 0; i < BITS_TO_LONGS(host->info->nb_pts); ++i) {
> >             host1x_sync_writel(host, 0xffffffffu,
> >                     HOST1X_SYNC_SYNCPT_THRESH_INT_DISABLE(i));
> >             host1x_sync_writel(host, 0xffffffffu,
> > 
> 
> Wouldn't this break in architectures with 64-bit longs?

Well, BIT_WORD() relies on BITS_PER_LONG too, so the current code is
broken for 64-bit architectures too.

> Probably the safest way would be to use DIV_ROUND_UP(host->info->nb_pts, 32),
> because we know there are 32 bits in each host1x register.

I agree. I hope there aren't any plans on making the registers 64 bits
wide in the future. Although they'd probably still be accessible as 32
bit values even then.

Thierry

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