netdev - Re: [PATCH net-next 14/14] net: stmmac: Activate Inband/PCS flag based on the selected iface

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Message-ID: <yma4bknen5jc6om56eorr44uuoqtziqvk4phds6cpkrubrs5dy@esxfxtz22egh>
Date: Fri, 2 Aug 2024 14:12:08 -0500
From: Andrew Halaney <ahalaney@...hat.com>
To: Russell King <rmk+kernel@...linux.org.uk>
Cc: Serge Semin <fancer.lancer@...il.com>, 
	Alexandre Torgue <alexandre.torgue@...s.st.com>, Alexei Starovoitov <ast@...nel.org>, bpf@...r.kernel.org, 
	Daniel Borkmann <daniel@...earbox.net>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Jesper Dangaard Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, 
	Jose Abreu <joabreu@...opsys.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-arm-msm@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com, 
	Maxime Coquelin <mcoquelin.stm32@...il.com>, netdev@...r.kernel.org, Paolo Abeni <pabeni@...hat.com>, 
	Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH net-next 14/14] net: stmmac: Activate Inband/PCS flag
 based on the selected iface

On Fri, Aug 02, 2024 at 11:47:37AM GMT, Russell King wrote:
> From: Serge Semin <fancer.lancer@...il.com>
> 
> The HWFEATURE.PCSSEL flag is set if the PCS block has been synthesized
> into the DW GMAC controller. It's always done if the controller supports
> at least one of the SGMII, TBI, RTBI PHY interfaces. If none of these
> interfaces support was activated during the IP-core synthesize the PCS
> block won't be activated either and the HWFEATURE.PCSSEL flag won't be
> set. Based on that the RGMII in-band status detection procedure
> implemented in the driver hasn't been working for the devices with the
> RGMII interface support and with none of the SGMII, TBI, RTBI PHY
> interfaces available in the device.
> 
> Fix that just by dropping the dma_cap.pcs flag check from the conditional
> statement responsible for the In-band/PCS functionality activation. If the
> RGMII interface is supported by the device then the in-band link status
> detection will be also supported automatically (it's always embedded into
> the RGMII RTL code). If the SGMII interface is supported by the device
> then the PCS block will be supported too (it's unconditionally synthesized
> into the controller). The later is also correct for the TBI/RTBI PHY
> interfaces.
> 
> Note while at it drop the netdev_dbg() calls since at the moment of the
> stmmac_check_pcs_mode() invocation the network device isn't registered. So
> the debug prints will be for the unknown/NULL device.
> 
> Signed-off-by: Serge Semin <fancer.lancer@...il.com>
> [rmk: fix build errors, only use PCS for SGMII if priv->dma_cap.pcs is set]
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Russell, did you add in the priv->dma_cap.pcs check with SGMII just
because it *is* expected to be set unconditionally when SGMII support is
there?

Always fan of less conditionals, so just curious as to your motivation
since Serge's message makes it seem like SGMII && dma_cap.pcs is a
redundant check.

Otherwise, looks good to me.

Thanks,
Andrew