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To:     Michael Walle <michael@walle.cc>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Andrew Lunn <andrew@lunn.ch>, Russell King <linux@armlinux.org.uk>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>
References: <20210210164746.26336-1-michael@walle.cc>
 <20210210164746.26336-6-michael@walle.cc>
From:   Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [PATCH net-next v2 5/9] net: phy: icplus: split IP101A/G driver
Message-ID: <56a7715b-24c6-fdda-d5ff-fe81be7b309a@gmail.com>
Date:   Wed, 10 Feb 2021 18:16:37 +0100
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On 10.02.2021 17:47, Michael Walle wrote:
> Unfortunately, the IP101A and IP101G share the same PHY identifier.
> While most of the functions are somewhat backwards compatible, there is
> for example the APS_EN bit on the IP101A but on the IP101G this bit
> reserved. Also, the IP101G has many more functionalities.
> 
> Deduce the model by accessing the page select register which - according
> to the datasheet - is not available on the IP101A. If this register is
> writable, assume we have an IP101G.
> 
> Split the combined IP101A/G driver into two separate drivers.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
> Changes since v1:
>  - use match_phy_device() as suggested by Heiner
> 
> Andrew, I've dropped your Reviewed-by because of this.
> 
>  drivers/net/phy/icplus.c | 69 ++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 67 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/phy/icplus.c b/drivers/net/phy/icplus.c
> index 036bac628b11..1bc9baa9048f 100644
> --- a/drivers/net/phy/icplus.c
> +++ b/drivers/net/phy/icplus.c
> @@ -44,6 +44,8 @@ MODULE_LICENSE("GPL");
>  #define IP101A_G_IRQ_DUPLEX_CHANGE	BIT(1)
>  #define IP101A_G_IRQ_LINK_CHANGE	BIT(0)
>  
> +#define IP101G_PAGE_CONTROL				0x14
> +#define IP101G_PAGE_CONTROL_MASK			GENMASK(4, 0)
>  #define IP101G_DIGITAL_IO_SPEC_CTRL			0x1d
>  #define IP101G_DIGITAL_IO_SPEC_CTRL_SEL_INTR32		BIT(2)
>  
> @@ -301,6 +303,58 @@ static irqreturn_t ip101a_g_handle_interrupt(struct phy_device *phydev)
>  	return IRQ_HANDLED;
>  }
>  
> +static int ip101a_g_has_page_register(struct phy_device *phydev)
> +{
> +	int oldval, val, ret;
> +
> +	oldval = phy_read(phydev, IP101G_PAGE_CONTROL);
> +	if (oldval < 0)
> +		return oldval;
> +
> +	ret = phy_write(phydev, IP101G_PAGE_CONTROL, 0xffff);
> +	if (ret)
> +		return ret;
> +
> +	val = phy_read(phydev, IP101G_PAGE_CONTROL);
> +	if (val < 0)
> +		return val;
> +
> +	ret = phy_write(phydev, IP101G_PAGE_CONTROL, oldval);
> +	if (ret)
> +		return ret;
> +
> +	return val == IP101G_PAGE_CONTROL_MASK;
> +}
> +
> +static int ip101a_g_match_phy_device(struct phy_device *phydev, bool ip101a)
> +{
> +	int ret;
> +
> +	if (phydev->phy_id != IP101A_PHY_ID)
> +		return 0;
> +
> +	/* The IP101A and the IP101G share the same PHY identifier.The IP101G
> +	 * seems to be a successor of the IP101A and implements more functions.
> +	 * Amongst other things there is a page select register, which is not
> +	 * available on the IP101A. Use this to distinguish these two.
> +	 */
> +	ret = ip101a_g_has_page_register(phydev);
> +	if (ret < 0)
> +		return ret;
> +
> +	return (ip101a) ? !ret : ret;

Simpler would be: return ip101a == !ret;

> +}
> +
> +static int ip101a_match_phy_device(struct phy_device *phydev)
> +{
> +	return ip101a_g_match_phy_device(phydev, true);
> +}
> +
> +static int ip101g_match_phy_device(struct phy_device *phydev)
> +{
> +	return ip101a_g_match_phy_device(phydev, false);
> +}
> +
>  static struct phy_driver icplus_driver[] = {
>  {
>  	PHY_ID_MATCH_MODEL(IP175C_PHY_ID),
> @@ -320,8 +374,19 @@ static struct phy_driver icplus_driver[] = {
>  	.suspend	= genphy_suspend,
>  	.resume		= genphy_resume,
>  }, {
> -	PHY_ID_MATCH_EXACT(IP101A_PHY_ID),
> -	.name		= "ICPlus IP101A/G",
> +	.name		= "ICPlus IP101A",
> +	.match_phy_device = ip101a_match_phy_device,
> +	/* PHY_BASIC_FEATURES */

These comments have once been automatically added as part of
a change in phy_driver structure. For new drivers they don't
make too much sense.

> +	.probe		= ip101a_g_probe,
> +	.config_intr	= ip101a_g_config_intr,
> +	.handle_interrupt = ip101a_g_handle_interrupt,
> +	.config_init	= ip101a_g_config_init,
> +	.soft_reset	= genphy_soft_reset,
> +	.suspend	= genphy_suspend,
> +	.resume		= genphy_resume,
> +}, {
> +	.name		= "ICPlus IP101G",
> +	.match_phy_device = ip101g_match_phy_device,
>  	/* PHY_BASIC_FEATURES */
>  	.probe		= ip101a_g_probe,
>  	.config_intr	= ip101a_g_config_intr,
>