netdev - Re: [PATCH net-next v4 1/2] net: phy: marvell10g: implement suspend/resume callbacks

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Message-ID: <20190403084614.GC3354@kwain>
Date:   Wed, 3 Apr 2019 10:46:14 +0200
From:   Antoine Tenart <antoine.tenart@...tlin.com>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        davem@...emloft.net, andrew@...n.ch, f.fainelli@...il.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        thomas.petazzoni@...tlin.com, maxime.chevallier@...tlin.com,
        gregory.clement@...tlin.com, miquel.raynal@...tlin.com,
        nadavh@...vell.com, stefanc@...vell.com, mw@...ihalf.com
Subject: Re: [PATCH net-next v4 1/2] net: phy: marvell10g: implement
 suspend/resume callbacks

Hi,

On Wed, Apr 03, 2019 at 07:09:55AM +0200, Heiner Kallweit wrote:
> On 03.04.2019 00:10, Russell King - ARM Linux admin wrote:
> > On Tue, Apr 02, 2019 at 08:17:16PM +0200, Heiner Kallweit wrote:
> >> On 02.04.2019 15:10, Antoine Tenart wrote:
> >>> This patch adds the suspend/resume callbacks for Marvell 10G PHYs. The
> >>> three PCS (base-t, base-r and 1000base-x) are set in low power (the PCS
> >>> are powered down) when the PHY isn't used.
> >>>
> >>> Signed-off-by: Antoine Tenart <antoine.tenart@...tlin.com>
> >>> ---
> >>>  drivers/net/phy/marvell10g.c | 12 +++++++++++-
> >>>  1 file changed, 11 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/net/phy/marvell10g.c b/drivers/net/phy/marvell10g.c
> >>> index 80678919641d..9ee033c8a12b 100644
> >>> --- a/drivers/net/phy/marvell10g.c
> >>> +++ b/drivers/net/phy/marvell10g.c
> >>> @@ -51,6 +51,8 @@ enum {
> >>>  	MV_AN_STAT1000		= 0x8001, /* 1000base-T status register */
> >>>  
> >>>  	/* Vendor2 MMD registers */
> >>> +	MV_V2_PORT_CTRL		= 0xf001,
> >>> +	MV_V2_PORT_CTRL_PWRDOWN = 0x0800,
> >>
> >> If this driver is touched again I think it would be good to change all
> >> such constants to BIT() and GENMASK(), ideally combined with the macros
> >> from bitfields.h. This makes it much easier to check the code against the
> >> datasheet. Apart from that:
> > 
> > Specifically, which constants are you talking about?
> > 
> > I think there's only MV_PCS_PAIRSWAP_MASK and MV_V2_TEMP_CTRL_MASK,
> > which would be confusing to change given that the following definitions
> > are values for the masked field.
> > 
> Exactly, MV_V2_TEMP_CTRL_MASK is a good example. My personal preference is
> to define the mask as GENMASK(15, 14) and the field values as 0 and 3.
> Then it's aligned with the datasheet that says:
> 15:14 Temperature Sense Enable, 11 = Disable
> Macros FIELD_GET and FIELD_PREP are perfect to deal with such fields.

I agree, I didn't used that to be consistent with what was already done
in the driver.

> > However, MV_V2_PORT_CTRL_PWRDOWN should be defined using BIT() in any
> > case.

Shouldn't MV_PCS_PAIRSWAP_AB also be defined using BIT()?

More generally, we could have all the register definitions using the 0x
values, the masks using GENMASK() and the values using a combination of
BIT() and (0x... << y). That would match what's usually done in other
drivers and improve the readability. (But I also recall being told not
to use GENMASK in net/, so it's up to you to decide).

I can send a following up patch if needed and if we agree on this.

Antoine

-- 
Antoine Ténart, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com