RE: [EXT] Re: [PATCH v1] ARM: imx6plus: enable internal routing of clk_enet_ref where possible

[Andy Duan <fugang.duan@nxp.com>]

From: Shawn Guo <shawnguo@kernel.org> Sent: Tuesday, June 23, 2020 7:54 PM
> Hi Fugang,
> 
> Can you take a look at this patch?  Thanks!
> 
The patch looks good.
Reviewed-by: Fugang Duan <fugang.duan@nxp.com>

> Shawn
> 
> On Sat, Jun 13, 2020 at 04:17:03PM -0400, Sven Van Asbroeck wrote:
> > On imx6, the ethernet reference clock (clk_enet_ref) can be generated
> > by either the imx6, or an external source (e.g. an oscillator or the
> > PHY). When generated by the imx6, the clock source (from ANATOP) must
> > be routed to the input of clk_enet_ref via two pads on the SoC,
> > typically via a dedicated track on the PCB.
> >
> > On an imx6 plus however, there is a new setting which enables this
> > clock to be routed internally on the SoC, from its ANATOP clock
> > source, straight to clk_enet_ref, without having to go through the SoC
> > pads.
> >
> > Board designs where the clock is generated by the imx6 should not be
> > affected by routing the clock internally. Therefore on a plus, we can
> > enable internal routing by default.
> >
> > To: Shawn Guo <shawnguo@kernel.org>
> > Cc: Sascha Hauer <s.hauer@pengutronix.de>
> > Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> > Cc: Fabio Estevam <festevam@gmail.com>
> > Cc: NXP Linux Team <linux-imx@nxp.com>
> > Cc: linux-arm-kernel@lists.infradead.org
> > Cc: linux-kernel@vger.kernel.org
> > Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
> > ---
> >  arch/arm/mach-imx/mach-imx6q.c              | 18
> ++++++++++++++++++
> >  include/linux/mfd/syscon/imx6q-iomuxc-gpr.h |  1 +
> >  2 files changed, 19 insertions(+)
> >
> > Tree: next-20200613
> >
> > diff --git a/arch/arm/mach-imx/mach-imx6q.c
> > b/arch/arm/mach-imx/mach-imx6q.c index 85c084a716ab..4d22567bb650
> > 100644
> > --- a/arch/arm/mach-imx/mach-imx6q.c
> > +++ b/arch/arm/mach-imx/mach-imx6q.c
> > @@ -203,6 +203,24 @@ static void __init imx6q_1588_init(void)
> >       else
> >               pr_err("failed to find fsl,imx6q-iomuxc-gpr regmap\n");
> >
> > +     /*
> > +      * On imx6 plus, enet_ref from ANATOP/CCM can be internally
> routed to
> > +      * be the PTP clock source, instead of having to be routed through
> > +      * pads.
> > +      * Board designs which route the ANATOP/CCM clock through pads
> are
> > +      * unaffected when routing happens internally. So on these designs,
> > +      * route internally by default.
> > +      */
> > +     if (clksel == IMX6Q_GPR1_ENET_CLK_SEL_ANATOP &&
> cpu_is_imx6q() &&
> > +                     imx_get_soc_revision() >=
> IMX_CHIP_REVISION_2_0) {
> > +             if (!IS_ERR(gpr))
> > +                     regmap_update_bits(gpr, IOMUXC_GPR5,
> > +
> IMX6Q_GPR5_ENET_TXCLK_SEL,
> > +
> IMX6Q_GPR5_ENET_TXCLK_SEL);
> > +             else
> > +                     pr_err("failed to find fsl,imx6q-iomuxc-gpr
> regmap\n");
> > +             }
> > +
> >       clk_put(enet_ref);
> >  put_ptp_clk:
> >       clk_put(ptp_clk);
> > diff --git a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> > b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> > index d4b5e527a7a3..eb65d48da0df 100644
> > --- a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> > +++ b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> > @@ -240,6 +240,7 @@
> >  #define IMX6Q_GPR4_IPU_RD_CACHE_CTL          BIT(0)
> >
> >  #define IMX6Q_GPR5_L2_CLK_STOP                       BIT(8)
> > +#define IMX6Q_GPR5_ENET_TXCLK_SEL            BIT(9)
> >  #define IMX6Q_GPR5_SATA_SW_PD                        BIT(10)
> >  #define IMX6Q_GPR5_SATA_SW_RST                       BIT(11)
> >
> > --
> > 2.17.1
> >