netdev - Re: [QUERY] : STMMAC Clocks

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Message-ID: <84b9c6b7-46b1-444f-b8db-d1f6d4fc5d1c@lunn.ch>
Date: Sat, 1 Mar 2025 00:38:04 +0100
From: Andrew Lunn <andrew@...n.ch>
To: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc: Russell King <linux@...linux.org.uk>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Giuseppe Cavallaro <peppe.cavallaro@...com>,
	Jose Abreu <joabreu@...opsys.com>, netdev <netdev@...r.kernel.org>
Subject: Re: [QUERY] : STMMAC Clocks

On Fri, Feb 28, 2025 at 09:51:15PM +0000, Lad, Prabhakar wrote:
> Hi All,
> 
> I am bit confused related clocks naming in with respect to STMMAC driver,
> 
> We have the below clocks in the binding doc:
> - stmmaceth
> - pclk
> - ptp_ref
> 
> But there isn't any description for this. Based on this patch [0]
> which isn't in mainline we have,
> - stmmaceth - system clock
> - pclk - CSR clock
> - ptp_ref - PTP reference clock.
> 
> [0] https://patches.linaro.org/project/netdev/patch/20210208135609.7685-23-Sergey.Semin@baikalelectronics.ru/
> 
> Can somebody please clarify on the above as I am planning to add a
> platform which supports the below clocks:
> - CSR clock
> - AXI system clock
> - Tx & Tx-180
> - Rx & Rx-180

Please take a look at the recent patches to stmmac for clock handling,
in particular the clocks used for RGMII

For the meaning of the clocks, you need to look at the vendors binding
document. Vendors tend to call the clocks whatever they want, rather
than have one consistent naming between vendors. The IP might be
licensed, but each vendor integrates it differently, inventing their
own clock names. It might of helped if Synopsis had requested in there
databook what each clock was called, so there was some consistency,
but this does not appear to of happened.

    Andrew