> On Fri, 2017-02-10 at 19:28 +0800, chin.yew.tan@xxxxxxxxx wrote:
> > From: Tan Chin Yew <chin.yew.tan@xxxxxxxxx>
> >
> > Sda-hold-time is an important parameter for tuning i2c to meet the
> > electrical specification especially for high speed. I2C with incorrect
> > sda-hold-time may cause lost arbitration error. Now, the driver is
> > able to get sda-hold-time for all the speed supported.
> >
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>
> Couple of nitpicks below.
>
> > Signed-off-by: Tan Chin Yew <chin.yew.tan@xxxxxxxxx>
> > ---
> > drivers/i2c/busses/i2c-designware-platdrv.c | 27
> > ++++++++++++++++++++-------
> > 1 file changed, 20 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> > b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index 6ce4313..aa33088 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -101,15 +101,28 @@ static int dw_i2c_acpi_configure(struct
> > platform_device *pdev)
> > dev->rx_fifo_depth = 32;
> >
> > /*
> > - * Try to get SDA hold time and *CNT values from an ACPI
> > method if
> > - * it exists for both supported speed modes.
> > + * Try to get SDA hold time and *CNT values from an ACPI
> > method for
> > + * selected speed modes.
> > */
> > - dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev-
> > >ss_lcnt, NULL);
> > - dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev-
> > >fs_lcnt,
> > + switch (dev->clk_freq) {
> > + case 100000:
> > + dw_i2c_acpi_params(pdev, "SSCN", &dev->ss_hcnt, &dev-
> > >ss_lcnt,
>
> > &dev->sda_hold_time);
>
> This indentation should go in a way that & character in the same column as p
> (in "p(s" context above).
I will realign the code according to suggestion.
>
> > - dw_i2c_acpi_params(pdev, "FPCN", &dev->fp_hcnt, &dev-
> > >fp_lcnt, NULL);
> > - dw_i2c_acpi_params(pdev, "HSCN", &dev->hs_hcnt, &dev-
> > >hs_lcnt, NULL);
> > -
> > + break;
> > + case 1000000:
> > + dw_i2c_acpi_params(pdev, "FPCN", &dev->fp_hcnt, &dev-
> > >fp_lcnt,
> > + &dev->sda_hold_time);
> > + break;
> > + case 3400000:
> > + dw_i2c_acpi_params(pdev, "HSCN", &dev->hs_hcnt, &dev-
> > >hs_lcnt,
> > + &dev->sda_hold_time);
> > + break;
>
> Can we prepend default with
>
> case 400000:
>
> here?
>
Yes, you are right, it is best not to load settings for speed mode that is
not supported.
> > + default:
>
>
> > + dw_i2c_acpi_params(pdev, "FMCN", &dev->fs_hcnt, &dev-
> > >fs_lcnt,
> > + &dev->sda_hold_time);
> > + break;
> > + }
> > +
> > id = acpi_match_device(pdev->dev.driver->acpi_match_table,
> > &pdev->dev);
> > if (id && id->driver_data)
> > dev->accessor_flags |= (u32)id->driver_data;
>
> --
> Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Intel Finland Oy
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