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

[Liam Beguin]

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 <l...@xiphos.com>
> > 
> > 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 <l...@xiphos.com>
> > ---
> > 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.kroge...@linux.intel.com>
> >   */
> >  #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 seems like a more concise notation.

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

I added the 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