Re: [PATCH v4 1/1] phy: tusb1210: use bitmasks to set VENDOR_SPECIFIC2

From: Liam Beguin
Date: Tue Sep 01 2020 - 10:48:50 EST


Hi Vinod,

On Mon Aug 31, 2020 at 7:08 AM EDT, Vinod Koul wrote:
> Hi Liam,
>
> On 22-08-20, 16:53, Liam Beguin wrote:
> > From: Liam Beguin <lvb@xxxxxxxxxx>
> >
> > Start by reading the content of the VENDOR_SPECIFIC2 register and update
> > each bit field based on device properties when defined.
> >
> > The use of bit masks prevents fields from overriding each other and
> > enables users to clear bits which are set by default, like datapolarity
> > in this instance.
> >
> > Signed-off-by: Liam Beguin <lvb@xxxxxxxxxx>
> > ---
> > Changes since v1:
> > - use set_mask_bits
> >
> > Changes since v2:
> > - fix missing bit shift dropped in v2
> > - rebase on 5.9-rc1
> >
> > Changes since v3:
> > - switch to u8p_replace_bits() since there's little reason to protect
> > against concurrent access
> >
> > drivers/phy/ti/phy-tusb1210.c | 27 ++++++++++++++-------------
> > 1 file changed, 14 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/phy/ti/phy-tusb1210.c b/drivers/phy/ti/phy-tusb1210.c
> > index d8d0cc11d187..a63213f5972a 100644
> > --- a/drivers/phy/ti/phy-tusb1210.c
> > +++ b/drivers/phy/ti/phy-tusb1210.c
> > @@ -7,15 +7,16 @@
> > * Author: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> > */
> > #include <linux/module.h>
> > +#include <linux/bitfield.h>
> > #include <linux/ulpi/driver.h>
> > #include <linux/ulpi/regs.h>
> > #include <linux/gpio/consumer.h>
> > #include <linux/phy/ulpi_phy.h>
> >
> > #define TUSB1210_VENDOR_SPECIFIC2 0x80
> > -#define TUSB1210_VENDOR_SPECIFIC2_IHSTX_SHIFT 0
> > -#define TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_SHIFT 4
> > -#define TUSB1210_VENDOR_SPECIFIC2_DP_SHIFT 6
> > +#define TUSB1210_VENDOR_SPECIFIC2_IHSTX_MASK GENMASK(3, 0)
> > +#define TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_MASK GENMASK(5, 4)
> > +#define TUSB1210_VENDOR_SPECIFIC2_DP_MASK BIT(6)
> >
> > struct tusb1210 {
> > struct ulpi *ulpi;
> > @@ -118,22 +119,22 @@ static int tusb1210_probe(struct ulpi *ulpi)
> > * diagram optimization and DP/DM swap.
> > */
> >
> > + reg = ulpi_read(ulpi, TUSB1210_VENDOR_SPECIFIC2);
> > +
> > /* High speed output drive strength configuration */
> > - device_property_read_u8(&ulpi->dev, "ihstx", &val);
> > - reg = val << TUSB1210_VENDOR_SPECIFIC2_IHSTX_SHIFT;
> > + if (!device_property_read_u8(&ulpi->dev, "ihstx", &val))
> > + u8p_replace_bits(&reg, val, (u8)TUSB1210_VENDOR_SPECIFIC2_IHSTX_MASK);
>
> Any reason for using u8p_replace_bits and not u8_replace_bits?
>

u8p_replace_bits seemed like a more concise notation.

> Also please drop the u8 casts above, they seem unnecessary here
>

I added the type casts to get rid of compilation warnings.

> >
> > /* High speed output impedance configuration */
> > - device_property_read_u8(&ulpi->dev, "zhsdrv", &val);
> > - reg |= val << TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_SHIFT;
> > + if (!device_property_read_u8(&ulpi->dev, "zhsdrv", &val))
> > + u8p_replace_bits(&reg, val, (u8)TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_MASK);
> >
> > /* DP/DM swap control */
> > - device_property_read_u8(&ulpi->dev, "datapolarity", &val);
> > - reg |= val << TUSB1210_VENDOR_SPECIFIC2_DP_SHIFT;
> > + if (!device_property_read_u8(&ulpi->dev, "datapolarity", &val))
> > + u8p_replace_bits(&reg, val, (u8)TUSB1210_VENDOR_SPECIFIC2_DP_MASK);
> >
> > - if (reg) {
> > - ulpi_write(ulpi, TUSB1210_VENDOR_SPECIFIC2, reg);
> > - tusb->vendor_specific2 = reg;
> > - }
> > + ulpi_write(ulpi, TUSB1210_VENDOR_SPECIFIC2, reg);
> > + tusb->vendor_specific2 = reg;
> >
> > tusb->phy = ulpi_phy_create(ulpi, &phy_ops);
> > if (IS_ERR(tusb->phy))
> >
> > base-commit: 9123e3a74ec7b934a4a099e98af6a61c2f80bbf5
> > --
> > 2.27.0
>
> --
> ~Vinod

Thanks,
Liam