linux-kernel - RE: [PATCH] ARM: at91: board-dt-sama5: add phy_fixup to override NAND_Tree which improperly strapp-in during the reset period.

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Date:	Wed, 17 Dec 2014 01:21:33 +0000
From:	"Yang, Wenyou" <Wenyou.Yang@...el.com>
To:	Florian Fainelli <f.fainelli@...il.com>,
	"Ferre, Nicolas" <Nicolas.FERRE@...el.com>
CC:	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] ARM: at91: board-dt-sama5: add phy_fixup to override
 NAND_Tree which improperly strapp-in during the reset period.

> -----Original Message-----
> From: Florian Fainelli [mailto:f.fainelli@...il.com]
> Sent: Wednesday, December 17, 2014 3:10 AM
> To: Ferre, Nicolas; Yang, Wenyou
> Cc: linux@....linux.org.uk; linux-arm-kernel@...ts.infradead.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH] ARM: at91: board-dt-sama5: add phy_fixup to override
> NAND_Tree which improperly strapp-in during the reset period.
> 
> On 16/12/14 02:20, Nicolas Ferre wrote:
> > Le 11/12/2014 08:31, Wenyou Yang a écrit :
> >> Appearance: On some SAMA5D4EK boards, after power up, the Eth1 doesn't
> work.
> >>
> >> Reason: The PIOE2 pin is connected to the NAND_Tree# of KSZ8081, But
> >> it outputs LOW during the reset period, which cause the NAND_Tree# enabled.
> >>
> >> Add phy_fixup() to disable NAND_Tree by overriding the Operation Mode
> >> Strap Override register(i.e. Register 16h) to clear the NAND_Tree bit.
> >>
> >> Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
> >
> > It seems correct to me.
> 
> Just one minor nit, see below
> 
> >
> > Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
> >
> > Anyway, I add Florian in the loop as he is the one who proposed this
> > solution. So it would have been good to have his feeling about the
> > implementation...
> >
> > Bye,
> >
> >> ---
> >>  arch/arm/mach-at91/board-dt-sama5.c |   18 ++++++++++++++++++
> >>  1 file changed, 18 insertions(+)
> >>
> >> diff --git a/arch/arm/mach-at91/board-dt-sama5.c
> >> b/arch/arm/mach-at91/board-dt-sama5.c
> >> index 8fb9ef5..97f7367 100644
> >> --- a/arch/arm/mach-at91/board-dt-sama5.c
> >> +++ b/arch/arm/mach-at91/board-dt-sama5.c
> >> @@ -17,6 +17,7 @@
> >>  #include <linux/of_platform.h>
> >>  #include <linux/phy.h>
> >>  #include <linux/clk-provider.h>
> >> +#include <linux/phy.h>
> >>
> >>  #include <asm/setup.h>
> >>  #include <asm/irq.h>
> >> @@ -26,8 +27,25 @@
> >>
> >>  #include "generic.h"
> >>
> >> +static int ksz8081_phy_fixup(struct phy_device *phy) {
> >> +	int value;
> >> +
> >> +	value = phy_read(phy, 0x16);
> >> +	value &= ~0x20;
> >> +	phy_write(phy, 0x16, value);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >>  static void __init sama5_dt_device_init(void)  {
> >> +	if (of_machine_is_compatible("atmel,sama5d4ek") &&
> >> +	   IS_ENABLED(CONFIG_PHYLIB)) {
> >> +		phy_register_fixup_for_id("fc028000.etherne:00",
> >> +						ksz8081_phy_fixup);
> 
> Matching the bus id certainly works, but I would rather match on your specific PHY
> device 32-bits OUI to make sure that if you ever change the PHY on a different
> design, this is not inadvertently writing to a register that is not micrel specific?
I don't think so.
Under the board compatible limitation, matching the bus id is enough for this case reason described above.

Moreover the PHY OUI is default value on the sama5d4ek.
MII_PHYSID1.15:0:  0x0022
MII_PHYSID2.15:10: 000101b

> 
> >> +	}
> >> +
> >>  	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
> >> }
> >>
> >>
> >
> >

Best Regards,
Wenyou Yang