linux-kernel - Re: [PATCH] net: thunderx: use proper interface type for RGMII

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Date:   Fri, 7 Feb 2020 22:02:09 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Tim Harvey <tharvey@...eworks.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        rrichter@...vell.com, linux-arm-kernel@...ts.infradead.org,
        davem@...emloft.net, sgoutham@...vell.com
Subject: Re: [PATCH] net: thunderx: use proper interface type for RGMII

On Fri, Feb 07, 2020 at 12:40:26PM -0800, Tim Harvey wrote:
> The configuration of the OCTEONTX XCV_DLL_CTL register via
> xcv_init_hw() is such that the RGMII RX delay is bypassed
> leaving the RGMII TX delay enabled in the MAC:
> 
> 	/* Configure DLL - enable or bypass
> 	 * TX no bypass, RX bypass
> 	 */
> 	cfg = readq_relaxed(xcv->reg_base + XCV_DLL_CTL);
> 	cfg &= ~0xFF03;
> 	cfg |= CLKRX_BYP;
> 	writeq_relaxed(cfg, xcv->reg_base + XCV_DLL_CTL);
> 
> This would coorespond to a interface type of PHY_INTERFACE_MODE_RGMII_RXID
> and not PHY_INTERFACE_MODE_RGMII.
> 
> Fixing this allows RGMII PHY drivers to do the right thing (enable
> RX delay in the PHY) instead of erroneously enabling both delays in the
> PHY.

Hi Tim

This seems correct. But how has it worked in the past? Does this
suggest there is PHY driver out there which is doing the wrong thing
when passed PHY_INTERFACE_MODE_RGMII?

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew