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Message-ID: <ZVzQh9ykusyknGgP@shell.armlinux.org.uk>
Date: Tue, 21 Nov 2023 15:45:11 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Tomer Maimon <tmaimon77@...il.com>
Cc: davem@...emloft.net, edumazet@...gle.com, robh+dt@...nel.org,
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Subject: Re: [PATCH v1 2/2] net: stmmac: Add NPCM support
On Tue, Nov 21, 2023 at 05:17:33PM +0200, Tomer Maimon wrote:
> Add Nuvoton NPCM BMC SoCs support to STMMAC dwmac driver.
>
> And modify MAINTAINERS to add a new F: entry for this driver.
>
> Signed-off-by: Tomer Maimon <tmaimon77@...il.com>
A few comments on this...
> +#define IND_AC_BA_REG 0x1FE
> +#define SR_MII_CTRL 0x3E0000
> +
> +#define PCS_SR_MII_CTRL_REG 0x0
> +#define PCS_SPEED_SELECT6 BIT(6)
> +#define PCS_AN_ENABLE BIT(12)
> +#define PCS_SPEED_SELECT13 BIT(13)
> +#define PCS_RST BIT(15)
include/uapi/linux/mii.h:
#define BMCR_SPEED1000 0x0040 /* MSB of Speed (1000) */
#define BMCR_ANENABLE 0x1000 /* Enable auto negotiation */
#define BMCR_SPEED100 0x2000 /* Select 100Mbps */
#define BMCR_RESET 0x8000 /* Reset to default state */
Look familiar? Maybe use the standard definitions for a standardised
register?
> +void npcm_dwmac_pcs_init(struct npcm_dwmac *dwmac, struct device *dev,
> + struct plat_stmmacenet_data *plat_dat)
> +{
> + u16 val;
> +
> + iowrite16((u16)(SR_MII_CTRL >> 9), dwmac->reg + IND_AC_BA_REG);
> + val = ioread16(dwmac->reg + PCS_SR_MII_CTRL_REG);
> + val |= PCS_RST;
> + iowrite16(val, dwmac->reg + PCS_SR_MII_CTRL_REG);
> +
> + while (val & PCS_RST)
> + val = ioread16(dwmac->reg + PCS_SR_MII_CTRL_REG);
What if the PCS never clears its reset bit? Maybe use
read_poll_timeout() ?
> +
> + val &= ~(PCS_AN_ENABLE);
> + iowrite16(val, dwmac->reg + PCS_SR_MII_CTRL_REG);
> +}
Also, maybe it's time to require new stmmac platform support to start
making use of the phylink PCS support rather than continuing to code its
own?
I notice, however, that you always disable inband signalling - please
explain why. Also, what protocol does the PCS use when communicating
with the PHY?
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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