linux-kernel - Re: [PATCH v3] phy: fsl-imx8mq-usb: add debugfs to access control register

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Message-ID: <rrmva3t4tesocitdrz5yfb35wer4htr5lkymzoyhjx4ajy7tt6@fbhlvrqzswd5>
Date: Fri, 16 Jan 2026 19:30:58 +0800
From: Xu Yang <xu.yang_2@....com>
To: Vinod Koul <vkoul@...nel.org>
Cc: Andrew Lunn <andrew@...n.ch>, neil.armstrong@...aro.org, 
	shawnguo@...nel.org, kernel@...gutronix.de, festevam@...il.com, jun.li@....com, 
	Frank.Li@....com, linux-phy@...ts.infradead.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] phy: fsl-imx8mq-usb: add debugfs to access control
 register

On Wed, Jan 14, 2026 at 03:09:54PM +0530, Vinod Koul wrote:
> On 08-01-26, 19:24, Andrew Lunn wrote:
> > On Thu, Jan 08, 2026 at 04:36:41PM +0800, Xu Yang wrote:
> > > The CR port is a simple 16-bit data/address parallel port that is
> > > provided for on-chip access to the control registers inside the
> > > USB 3.0 femtoPHY[1]. While access to these registers is not required
> > > for normal PHY operation, this interface enables you to access
> > > some of the PHY’s diagnostic features during normal operation or
> > > to override some basic PHY control signals.
> > > 
> > > 3 debugfs files are created to read and write control registers,
> > > all use hexadecimal format:
> > > ctrl_reg_base: the register offset to write, or the start offset
> > >                to read.
> > > ctrl_reg_count: how many continuous registers to be read.
> > > ctrl_reg_value: read to show the continuous registers value from
> > >                 the offset in ctrl_reg_base, to ctrl_reg_base
> > >                 + ctrl_reg_count - 1, one line for one register.
> > >                 when write, override the register at ctrl_reg_base,
> > >                 one time can only change one 16bits register.
> > > 
> > > Link[1]: https://www.synopsys.com/dw/doc.php/phy/usb3.0/femto/phy/x652_usb3_ss14lpp_18_ns/4.07a/dwc_usb3.0_femtophy_ss14lpp_08V18V_x1_databook.pdf
> > 
> > Please don't ignore my comments to V2. Think about the code split
> > between the generic IP licensed from Synopsys and the vendor specific
> > code used for integration into the SoC. You want to avoid making a
> > mess you later need to cleanup because somebody else licensed the same
> > IP core from Synopsys, and need to put their own vendor specific
> > integration code around the generic code.
> 
> Agree with Andrew here, please do mix, splitting would be better

OK, will try.

Thanks,
Xu Yang

> 
> > 
> >     Andrew
> 
> -- 
> ~Vinod