linux-kernel - Re: [PATCH v7 3/4] phy: rockchip-pcie: Enable all four lanes if required

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Message-ID: <aGLPeZn9ZSw3FurH@geday>
Date: Mon, 30 Jun 2025 14:55:05 -0300
From: Geraldo Nascimento <geraldogabriel@...il.com>
To: Robin Murphy <robin.murphy@....com>
Cc: linux-rockchip@...ts.infradead.org,
	Shawn Lin <shawn.lin@...k-chips.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Heiko Stuebner <heiko@...ech.de>, Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Rick wertenbroek <rick.wertenbroek@...il.com>,
	linux-phy@...ts.infradead.org, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 3/4] phy: rockchip-pcie: Enable all four lanes if
 required

On Mon, Jun 30, 2025 at 02:48:25PM +0100, Robin Murphy wrote:
> On 29/06/2025 9:58 pm, Geraldo Nascimento wrote:
> > Current code enables only Lane 0 because pwr_cnt will be incremented on
> > first call to the function. Let's reorder the enablement code to enable
> > all 4 lanes through GRF.
> 
> As usual the TRM isn't very clear, but the way it describes the 
> GRF_SOC_CON_5_PCIE bits does suggest they're driving external input 
> signals of the phy block, so it seems reasonable that it could be OK to 
> update the register itself without worrying about releasing the phy from 
> reset first. In that case I'd agree this seems the cleanest fix, and if 
> it works empirically then I think I'm now sufficiently convinced too;
> 
> Reviewed-by: Robin Murphy <robin.murphy@....com>

Hi Robin and Neil,

Thank you both for the positive reviews and the effort.

I must admit however that it looks like this patch was lifted verbatim
from Armbian and I'm missing the Signed-off-by from the original author.

As Robin may attest, I initially started by blindingly enabling all
lanes which, of course, is no good. I tried a suggestion by Robin which
did not work, and eventually settled on this Armbian solution, which at
least has got some battle-testing.

I already contacted Valmintas Paliksa, the original author of the patch,
and asked permission to use his Signed-off-by. I'm aware I could probably
use the Signed-off-by without strict permission, but it does not feel
right to me.

Thanks,
Geraldo Nascimento