On Sun, Jan 23, 2022 at 05:22:18PM +0530, Vinod Koul wrote:
> On 17-01-22, 01:26, Ansuel Smith wrote:
> > Convert latch function to readl pool macro to tidy things up.
> >
> > Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>
> > ---
> > drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c | 17 +++++------------
> > 1 file changed, 5 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c b/drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c
> > index 6788e0e8272a..ab2d1431546d 100644
> > --- a/drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c
> > +++ b/drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c
> > @@ -112,6 +112,9 @@
> > #define SS_CR_READ_REG BIT(0)
> > #define SS_CR_WRITE_REG BIT(0)
> >
> > +#define LATCH_SLEEP 40
> > +#define LATCH_TIMEOUT 100
> > +
> > struct usb_phy {
> > void __iomem *base;
> > struct device *dev;
> > @@ -156,19 +159,9 @@ static inline void usb_phy_write_readback(struct usb_phy *phy_dwc3,
> >
> > static int wait_for_latch(void __iomem *addr)
> > {
> > - u32 retry = 10;
> > -
> > - while (true) {
> > - if (!readl(addr))
> > - break;
>
> we break if read returns non zero value...
>
> Do you know what is the value expected?
>
If I understand the logic here, we write a value and we wait for it to
get applied. To confirm that we execute a writel and then we readl the
same address until it does return a value. That is the way used to
understand that the write process has finished and that the value has
been applied/we can write again.
> > -
> > - if (--retry == 0)
> > - return -ETIMEDOUT;
> > -
> > - usleep_range(10, 20);
> > - }
> > + u32 val;
>
> Okay this contains garbage..
I think I didn't understand, val value will get replaced by readl in
the pool_timeout function.
> >
> > - return 0;
> > + return readl_poll_timeout(addr, val, !val, LATCH_SLEEP, LATCH_TIMEOUT);
>
> and we are waiting for it read a garbage value!
>
Again could be very confused and wrong but the pool_timeout macro does
the exact same thing of the wait_for_latch function with th only
difference of handling the sleep differently. We put in val the return
of readl and the break condition as !val. Or I didn't understand the
concern about garbage value.
>
> --
> ~Vinod
--
Ansuel
