linux-kernel - Re: [PATCH v1 1/1] phy: tusb1210: use bitmasks to set VENDOR

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Message-Id: <C46HLW9JFSYI.2YB0NSAHXDI3A@atris>
Date:   Tue, 14 Jul 2020 12:28:34 -0400
From:   "Liam Beguin" <liambeguin@...il.com>
To:     "Vinod Koul" <vkoul@...nel.org>
Cc:     <kishon@...com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/1] phy: tusb1210: use bitmasks to set
 VENDOR_SPECIFIC2

Hi Vinod,

On Mon Jul 13, 2020 at 10:38 AM Vinod Koul wrote:
> On 01-07-20, 21:06, Liam Beguin wrote:
> > From: Liam Beguin <lvb@...hos.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 <lvb@...hos.com>
> > ---
> >  drivers/phy/ti/phy-tusb1210.c | 29 ++++++++++++++++-------------
> >  1 file changed, 16 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/phy/ti/phy-tusb1210.c b/drivers/phy/ti/phy-tusb1210.c
> > index d8d0cc11d187..a957655ebd36 100644
> > --- a/drivers/phy/ti/phy-tusb1210.c
> > +++ b/drivers/phy/ti/phy-tusb1210.c
> > @@ -13,9 +13,9 @@
> >  #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	0x0f
> > +#define TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_MASK	0x30
> 
> Why not be better and use GENMASK(3, 0) and GENMASK(5, 4) for these
> 

Will update, I didn't know about GENMASK.

> > +#define TUSB1210_VENDOR_SPECIFIC2_DP_MASK	BIT(6)
> >  
> >  struct tusb1210 {
> >  	struct ulpi *ulpi;
> > @@ -118,22 +118,25 @@ 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))
> > +		reg = (reg & ~TUSB1210_VENDOR_SPECIFIC2_IHSTX_MASK) |
> > +			(val & TUSB1210_VENDOR_SPECIFIC2_IHSTX_MASK);
> 
> It would be better to use a helper to do this
> 

I found set_mask_bits(), will use that instead.

> >  
> >  	/* 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))
> > +		reg = (reg & ~TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_MASK) |
> > +			(val & 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))
> > +		reg = (reg & ~TUSB1210_VENDOR_SPECIFIC2_DP_MASK) |
> > +			(val & 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: cd77006e01b3198c75fb7819b3d0ff89709539bb
> 
> fatal: bad object cd77006e01b3198c75fb7819b3d0ff89709539bb in
> linux-phy.git
> 

Sorry about that, I'll rebase on the latest linux-phy.git

Thanks for your time,
Liam

> -- 
> ~Vinod