Re: [RFC PATCH net] net: dsa: mt7530: move PLL setup out of port 6 pad configuration

["Arınç ÜNAL" <arinc.unal@arinc9.com>]

On 4.03.2023 15:54, arinc9.unal@gmail.com wrote:
> From: Arınç ÜNAL <arinc.unal@arinc9.com>
> 
> Move the PLL setup of the MT7530 switch out of the pad configuration of
> port 6 to mt7530_setup, after reset.
> 
> This fixes the improper initialisation of the switch when only port 5 is
> used as a CPU port.
> 
> Add supported phy modes of port 5 on the PLL setup.
> 
> Remove now incorrect comment regarding P5 as GMAC5.
> 
> Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
> Fixes: 38f790a80560 ("net: dsa: mt7530: Add support for port 5")
> Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
> ---
> 
> I'm trying to mimic this change by Alexander [0] for the MT7530 switch.
> This is already the case for MT7530 and MT7531 on the MediaTek ethernet
> driver on U-Boot [1] [2].
> 
> [0] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=42bc4fafe359ed6b73602b7a2dba0dd99588f8ce
> [1] https://github.com/u-boot/u-boot/blob/a94ab561e2f49a80d8579930e840b810ab1a1330/drivers/net/mtk_eth.c#L729
> [2] https://github.com/u-boot/u-boot/blob/a94ab561e2f49a80d8579930e840b810ab1a1330/drivers/net/mtk_eth.c#L903
> 
> There are some parts I couldn't figure out myself with my limited C
> knowledge. I've pointed them out on the code. Vladimir, could you help?
> 
> There is a lot of code which is only needed for port 6 or trgmii on port 6,
> but runs whether port 6 or trgmii is used or not. For now, the best I can
> do is to fix port 5 so it works without port 6 being used.
> 
> The U-Boot driver seems to be much more organised so it could be taken as
> a reference to sort out this DSA driver further.
> 
> Also, now that the pad setup for mt7530 is also moved somewhere else, can
> we completely get rid of @pad_setup?
> 
> Arınç
> 
> ---
>   drivers/net/dsa/mt7530.c | 46 +++++++++++++++++++++++++++++-----------
>   1 file changed, 34 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 0e99de26d159..fb20ce4f443e 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -395,9 +395,8 @@ mt7530_fdb_write(struct mt7530_priv *priv, u16 vid,
>   
>   /* Setup TX circuit including relevant PAD and driving */
>   static int
> -mt7530_pad_clk_setup(struct dsa_switch *ds, phy_interface_t interface)
> +mt7530_pad_clk_setup(struct mt7530_priv *priv, phy_interface_t interface)
>   {
> -	struct mt7530_priv *priv = ds->priv;
>   	u32 ncpo1, ssc_delta, trgint, i, xtal;
>   
>   	xtal = mt7530_read(priv, MT7530_MHWTRAP) & HWTRAP_XTAL_MASK;
> @@ -409,9 +408,32 @@ mt7530_pad_clk_setup(struct dsa_switch *ds, phy_interface_t interface)
>   		return -EINVAL;
>   	}
>   
> +	/* Is setting trgint to 0 really needed for the !trgint check? */
> +	trgint = 0;
> +
> +	/* FIXME: run this switch if p5 is defined on the devicetree */
> +	/* and change interface to the phy-mode of port 5 */
> +	switch (interface) {
> +	case PHY_INTERFACE_MODE_GMII:
> +		/* PLL frequency: 125MHz */
> +		ncpo1 = 0x0c80;
> +		break;
> +	case PHY_INTERFACE_MODE_MII:
> +		break;
> +	case PHY_INTERFACE_MODE_RGMII:
> +		/* PLL frequency: 125MHz */
> +		ncpo1 = 0x0c80;
> +		break;
> +	default:
> +		dev_err(priv->dev, "xMII interface %d not supported\n",
> +			interface);
> +		return -EINVAL;
> +	}
> +
> +	/* FIXME: run this switch if p6 is defined on the devicetree */
> +	/* and change interface to the phy-mode of port 6 */
>   	switch (interface) {
>   	case PHY_INTERFACE_MODE_RGMII:
> -		trgint = 0;
>   		/* PLL frequency: 125MHz */
>   		ncpo1 = 0x0c80;
>   		break;
> @@ -2172,7 +2194,11 @@ mt7530_setup(struct dsa_switch *ds)
>   		     SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |
>   		     SYS_CTRL_REG_RST);
>   
> -	/* Enable Port 6 only; P5 as GMAC5 which currently is not supported */
> +	/* Setup switch core pll */
> +	/* FIXME: feed the phy-mode of port 5 and 6, if the ports are defined on the devicetree */
> +	mt7530_pad_clk_setup(priv, interface);

Unlike mt7531_pll_setup, there are return codes on mt7530_pad_clk_setup 
so we may need to check for the return code here.

Arınç