Re: [PATCH v2 7/8] PCI: brcmstb: Make two changes in MDIO register fields

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Fri, Feb 14, 2025 at 12:39:35PM -0500, Jim Quinlan wrote:
> The HW team has decided to "tighten" some field definitions in the MDIO
> packet format.  Fortunately these two changes may be made in a backwards
> compatible manner.
> 
> The CMD field used to be 12 bits and now is one.  This change is backwards
> compatible because the field's starting bit position is unchanged and the
> only commands we've used have values 0 and 1.
> 
> The PORT field's width has been changed from four to five bits.  When
> written, the new bit is not contiguous with the other four.  Fortunately,
> this change is backwards compatible because we have never used anything
> other than 0 for the port field's value.
> 
> Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/pci/controller/pcie-brcmstb.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index 923ac1a03f85..cb897d4b2579 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -175,8 +175,9 @@
>  #define MDIO_PORT0			0x0
>  #define MDIO_DATA_MASK			0x7fffffff
>  #define MDIO_PORT_MASK			0xf0000
> +#define MDIO_PORT_EXT_MASK		0x200000
>  #define MDIO_REGAD_MASK			0xffff
> -#define MDIO_CMD_MASK			0xfff00000
> +#define MDIO_CMD_MASK			0x00100000
>  #define MDIO_CMD_READ			0x1
>  #define MDIO_CMD_WRITE			0x0
>  #define MDIO_DATA_DONE_MASK		0x80000000
> @@ -327,6 +328,7 @@ static u32 brcm_pcie_mdio_form_pkt(int port, int regad, int cmd)
>  {
>  	u32 pkt = 0;
>  
> +	pkt |= FIELD_PREP(MDIO_PORT_EXT_MASK, port >> 4);
>  	pkt |= FIELD_PREP(MDIO_PORT_MASK, port);
>  	pkt |= FIELD_PREP(MDIO_REGAD_MASK, regad);
>  	pkt |= FIELD_PREP(MDIO_CMD_MASK, cmd);
> -- 
> 2.43.0
> 

-- 
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