[linux-yocto] [PATCH 1/3] drivers/misc: Axxia MTC Driver Memory Initialization Check

[John Jacques]

Bruce,

I agree with you on both.  I spoke to Sreedevi and there's isn't a reason
she didn't use readl().  As for the delay, we expect about 2 us.  So, I
assume udelay(1) would be appropriate?  If both are okay (readl() instead
of direct access and udelay(1)), I'll update the commit.

Thanks for looking at this!

On Tue, Aug 23, 2016 at 10:08 AM, Dragomir, Daniel <
Daniel.Dragomir at windriver.com> wrote:

> Adding John Jacques, the proper person to respond on this.
>
> Regards,
> Daniel
> ________________________________________
> From: Winkler, Tomas [tomas.winkler at intel.com]
> Sent: Monday, August 22, 2016 12:52 PM
> To: Dragomir, Daniel; linux-yocto at yoctoproject.org
> Subject: RE: [linux-yocto] [PATCH 1/3] drivers/misc: Axxia MTC Driver
> Memory    Initialization Check
>
> >
> > Axxia MTC driver changes:
> >  - Memory initialization completion check added
> >  - ECC error status clearing added
> >
> > Signed-off-by: Sreedevi Joshi <sreedevi.joshi at intel.com>
> > ---
> >  drivers/misc/lsi-mtc.c | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> >
> > diff --git a/drivers/misc/lsi-mtc.c b/drivers/misc/lsi-mtc.c index
> > 55c3403..f4fbe6f 100644
> > --- a/drivers/misc/lsi-mtc.c
> > +++ b/drivers/misc/lsi-mtc.c
> > @@ -31,6 +31,7 @@
> >  #include <linux/string.h>
> >  #include "linux/lsi_mtc_ioctl.h"
> >
> > +#define MTC_POLL_TIMEOUT (msecs_to_jiffies(1000))
> >
> >  /*
> >     device tree node:
> > @@ -4114,6 +4115,8 @@ static long _mtc_config(struct mtc_device *dev,
> > struct lsi_mtc_cfg_t *pMTCCfg)
> >       struct ncp_axis_mtc_MTC_CONFIG0_REG_ADDR_r_t cfg0 = { 0 };
> >       struct ncp_axis_mtc_MTC_CONFIG1_REG_ADDR_r_t cfg1 = { 0 };
> >       struct ncp_axis_mtc_MTC_EXECUTE1_REG_ADDR_r_t exec1 = { 0 };
> > +     u32     init_reg = { 0 };
> > +     unsigned long tmo = 0;
> >
> >       if ((!pMTCCfg) || (!dev))
> >               return -EINVAL;
> > @@ -4129,6 +4132,21 @@ static long _mtc_config(struct mtc_device *dev,
> > struct lsi_mtc_cfg_t *pMTCCfg)
> >       exec1.sw_reset = 1;
> >       dev->regs->execute = *((u32 *) &exec1);
> >       dev->regs->mem_init = 0x202;
> > +     /* wait for the init to complete */
> > +     tmo = jiffies + MTC_POLL_TIMEOUT;
> > +     do {
> > +             init_reg = *(&(dev->regs->mem_init));+
>
> I'm not familiar with this code but I don't think this is the way to read
> a register , why not using readl(), you are at least missing memory barrier
> here.
>
> > +             if ((init_reg & 0x101) == 0x101)
> > +                     break;
> > +     } while (time_before(jiffies, tmo));
>
> This is busy loop, how fast is that going to settle ?
>
> > +
> > +     if ((init_reg & 0x101) != 0x101) {
> > +             pr_debug("warning: mem_init failed value=0x%x
> > (expected:0x101)\n",
> > +                            init_reg);
> > +     }
> > +
> > +     /* clear ECC interrupt status */
> > +     dev->regs->ecc_int_status = 0xF;
> >
> >       /* 3. config MTC */
> >       cfg0 =
> > --
> > 2.7.4
> >
> > --
> > _______________________________________________
> > linux-yocto mailing list
> > linux-yocto at yoctoproject.org
> > https://lists.yoctoproject.org/listinfo/linux-yocto
> --
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