netdev - Re: [PATCH net-next v2 3/3] net: stmmac: Add DWMAC glue layer for Renesas GBETH

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Message-ID: <Z81WVNGlvRNW5JFk@shell.armlinux.org.uk>
Date: Sun, 9 Mar 2025 08:50:28 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Giuseppe Cavallaro <peppe.cavallaro@...com>,
	Jose Abreu <joabreu@...opsys.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
	Biju Das <biju.das.jz@...renesas.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH net-next v2 3/3] net: stmmac: Add DWMAC glue layer for
 Renesas GBETH

On Sat, Mar 08, 2025 at 08:09:21PM +0000, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> Add the DWMAC glue layer for the GBETH IP found in the Renesas RZ/V2H(P)
> SoC.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
> v1->v2
> - Dropped __initconst for renesas_gbeth_clks array
> - Added clks_config callback
> - Dropped STMMAC_FLAG_RX_CLK_RUNS_IN_LPI flag as this needs
>   investigation.

I thought you had got to the bottom of this, and it was a bug in your
clock driver?

> + * The Rx and Tx clocks are supplied as follows for the GBETH IP.
> + *
> + *                         Rx / Tx
> + *   -------+------------- on / off -------
> + *          |
> + *          |            Rx-180 / Tx-180
> + *          +---- not ---- on / off -------

Thanks for the diagram.

> +struct renesas_gbeth {
> +	struct device *dev;
> +	void __iomem *regs;
> +	unsigned int num_clks;
> +	struct clk *clk_tx_i;
> +	struct clk_bulk_data *clks;
> +	struct reset_control *rstc;
> +};

If you stored a pointer to struct plat_stmmacenet_data, then you
wouldn't need num_clks, clk_tx_i or clks. If you look at
dwmac-dwc-qos-eth.c, I recently added a helper (dwc_eth_find_clk())
which could be made generic.

You can then include the clk_tx_i clock in the bulk clock, and
use the helper to set plat_dat->clk_tx_i.

> +	plat_dat->flags |= STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY |
> +			   STMMAC_FLAG_EN_TX_LPI_CLOCKGATING |

Didn't I send you a patch that provides
STMMAC_FLAG_EN_TX_LPI_CLK_PHY_CAP so we can move towards the PHY
saying whether it permits the TX clock to be disabled?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!