Re: [PATCH net-next 3/3] net: stmmac: Add RK3566/RK3568 SoC support

From: "Heiko Stübner" <heiko@sntech.de>
To: Ezequiel Garcia <ezequiel@collabora.com>,
	Chen-Yu Tsai <wens213@gmail.com>
Cc: Peter Geis <pgwipeout@gmail.com>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Jose Abreu <joabreu@synopsys.com>,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	David Wu <david.wu@rock-chips.com>,
	kernel@collabora.com
Subject: Re: [PATCH net-next 3/3] net: stmmac: Add RK3566/RK3568 SoC support
Date: Wed, 14 Apr 2021 18:35:41 +0200	[thread overview]
Message-ID: <11053800.MucGe3eQFb@diego> (raw)
In-Reply-To: <CAGb2v67ZBR=XDFPeXQc429HNu_dbY__-KN50tvBW44fXMs78_w@mail.gmail.com>

Am Mittwoch, 14. April 2021, 18:33:12 CEST schrieb Chen-Yu Tsai:
> On Thu, Apr 15, 2021 at 12:14 AM Ezequiel Garcia <ezequiel@collabora.com> wrote:
> >
> > Hi Peter, Heiko,
> >
> > On Wed, 2021-04-14 at 13:15 +0200, Heiko Stübner wrote:
> > > Am Mittwoch, 14. April 2021, 13:03:25 CEST schrieb Peter Geis:
> > > > On Tue, Apr 13, 2021 at 7:37 PM Ezequiel Garcia <ezequiel@collabora.com> wrote:
> > > > > > > +static void rk3566_set_to_rmii(struct rk_priv_data *bsp_priv)
> > > > > > > +{
> > > > > > > +       struct device *dev = &bsp_priv->pdev->dev;
> > > > > > > +
> > > > > > > +       if (IS_ERR(bsp_priv->grf)) {
> > > > > > > +               dev_err(dev, "%s: Missing rockchip,grf property\n", __func__);
> > > > > > > +               return;
> > > > > > > +       }
> > > > > > > +
> > > > > > > +       regmap_write(bsp_priv->grf, RK3568_GRF_GMAC1_CON1,
> > > > > > > +                    RK3568_GMAC_PHY_INTF_SEL_RMII);
> > > > > > > +}
> > > > > > > +
> > > > > > > +static void rk3568_set_to_rgmii(struct rk_priv_data *bsp_priv,
> > > > > > > +                               int tx_delay, int rx_delay)
> > > > > > > +{
> > > > > > > +       struct device *dev = &bsp_priv->pdev->dev;
> > > > > > > +
> > > > > > > +       if (IS_ERR(bsp_priv->grf)) {
> > > > > > > +               dev_err(dev, "Missing rockchip,grf property\n");
> > > > > > > +               return;
> > > > > > > +       }
> > > > > > > +
> > > > > > > +       regmap_write(bsp_priv->grf, RK3568_GRF_GMAC0_CON1,
> > > > > > > +                    RK3568_GMAC_PHY_INTF_SEL_RGMII |
> > > > > > > +                    RK3568_GMAC_RXCLK_DLY_ENABLE |
> > > > > > > +                    RK3568_GMAC_TXCLK_DLY_ENABLE);
> > > > > > > +
> > > > > > > +       regmap_write(bsp_priv->grf, RK3568_GRF_GMAC0_CON0,
> > > > > > > +                    RK3568_GMAC_CLK_RX_DL_CFG(rx_delay) |
> > > > > > > +                    RK3568_GMAC_CLK_TX_DL_CFG(tx_delay));
> > > > > > > +
> > > > > > > +       regmap_write(bsp_priv->grf, RK3568_GRF_GMAC1_CON1,
> > > > > > > +                    RK3568_GMAC_PHY_INTF_SEL_RGMII |
> > > > > > > +                    RK3568_GMAC_RXCLK_DLY_ENABLE |
> > > > > > > +                    RK3568_GMAC_TXCLK_DLY_ENABLE);
> > > > > > > +
> > > > > > > +       regmap_write(bsp_priv->grf, RK3568_GRF_GMAC1_CON0,
> > > > > > > +                    RK3568_GMAC_CLK_RX_DL_CFG(rx_delay) |
> > > > > > > +                    RK3568_GMAC_CLK_TX_DL_CFG(tx_delay));
> > > > > >
> > > > > > Since there are two GMACs on the rk3568, and either, or, or both may
> > > > > > be enabled in various configurations, we should only configure the
> > > > > > controller we are currently operating.
> > > >
> > > > Perhaps we should have match data (such as reg = <0>, or against the
> > > > address) to identify the individual controllers.
> > >
> > > Hmm, "reg" will be used by the actual mmio address of the controller,
> > > so matching against that should be the way I guess.
> > >
> > > We're already doing something similar for dsi:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c#n1170
> > >
> >
> > I have to admit, I'm not a fan of hardcoding the registers in the kernel.
> >
> > David Wu solved this in the downstream kernel by using bus_id,
> > which parses the devicetree "ethernet@0" node, i.e.:
> >
> >   plat->bus_id = of_alias_get_id(np, "ethernet");
> 
> What happens when one adds another ethernet controller (USB or PCIe) to
> the board and wants to change the numbering order?
> 
> Or maybe only the second ethernet controller is routed on some board
> and the submitter / vendor wants that one to be ethernet0, because
> it's the only usable controller?

Which matches a discussion I had with Arnd about the mmc numbering.
I.e. there the first mmc device is supposed to be mmc0 and so on,
without gaps - for probably the same reasons.

> 
> This seems even more fragile than hardcoding the registers.
> 
> Regards
> ChenYu
> 