netdev - Re: [Patch net-next v13 07/13] net: dsa: microchip: add LAN937x SPI driver

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Date:   Thu, 5 May 2022 10:32:17 +0000
From:   <Arun.Ramadoss@...rochip.com>
To:     <olteanv@...il.com>
CC:     <songliubraving@...com>, <linux-kernel@...r.kernel.org>,
        <bpf@...r.kernel.org>, <daniel@...earbox.net>, <ast@...nel.org>,
        <robh+dt@...nel.org>, <andrew@...n.ch>,
        <devicetree@...r.kernel.org>, <linux@...linux.org.uk>,
        <andrii@...nel.org>, <UNGLinuxDriver@...rochip.com>,
        <john.fastabend@...il.com>, <vivien.didelot@...il.com>,
        <f.fainelli@...il.com>, <kuba@...nel.org>, <kpsingh@...nel.org>,
        <edumazet@...gle.com>, <pabeni@...hat.com>,
        <netdev@...r.kernel.org>, <kafai@...com>, <yhs@...com>,
        <krzysztof.kozlowski+dt@...aro.org>, <davem@...emloft.net>,
        <Woojung.Huh@...rochip.com>
Subject: Re: [Patch net-next v13 07/13] net: dsa: microchip: add LAN937x SPI
 driver

Hi Vladimir,
Thanks for the comment.

On Wed, 2022-05-04 at 23:07 +0300, Vladimir Oltean wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
> 
> On Wed, May 04, 2022 at 08:47:49PM +0530, Arun Ramadoss wrote:
> > This patch add the SPI driver for the LAN937x switches. It uses the
> > lan937x_main.c and lan937x_dev.c functions.
> > 
> > Signed-off-by: Arun Ramadoss <arun.ramadoss@...rochip.com>
> > ---
> >  drivers/net/dsa/microchip/Makefile      |   1 +
> >  drivers/net/dsa/microchip/ksz_common.h  |   1 +
> >  drivers/net/dsa/microchip/lan937x_dev.c |   7 +
> >  drivers/net/dsa/microchip/lan937x_spi.c | 236
> > ++++++++++++++++++++++++
> >  4 files changed, 245 insertions(+)
> >  create mode 100644 drivers/net/dsa/microchip/lan937x_spi.c
> > 
> > diff --git a/drivers/net/dsa/microchip/Makefile
> > b/drivers/net/dsa/microchip/Makefile
> > index d32ff38dc240..28d8eb62a795 100644
> > --- a/drivers/net/dsa/microchip/Makefile
> > +++ b/drivers/net/dsa/microchip/Makefile
> > @@ -10,3 +10,4 @@ obj-$(CONFIG_NET_DSA_MICROCHIP_KSZ8863_SMI) +=
> > ksz8863_smi.o
> >  obj-$(CONFIG_NET_DSA_MICROCHIP_LAN937X)              += lan937x.o
> >  lan937x-objs := lan937x_dev.o
> >  lan937x-objs += lan937x_main.o
> > +lan937x-objs += lan937x_spi.o
> > diff --git a/drivers/net/dsa/microchip/ksz_common.h
> > b/drivers/net/dsa/microchip/ksz_common.h
> > index 5671f580948d..fd9e0705d2d2 100644
> > --- a/drivers/net/dsa/microchip/ksz_common.h
> > +++ b/drivers/net/dsa/microchip/ksz_common.h
> > @@ -151,6 +151,7 @@ void ksz_switch_remove(struct ksz_device *dev);
> >  int ksz8_switch_register(struct ksz_device *dev);
> >  int ksz9477_switch_register(struct ksz_device *dev);
> >  int lan937x_switch_register(struct ksz_device *dev);
> > +int lan937x_check_device_id(struct ksz_device *dev);
> > 
> >  void ksz_update_port_member(struct ksz_device *dev, int port);
> >  void ksz_init_mib_timer(struct ksz_device *dev);
> > diff --git a/drivers/net/dsa/microchip/lan937x_dev.c
> > b/drivers/net/dsa/microchip/lan937x_dev.c
> > index 3f1797cc1d16..f430a8711775 100644
> > --- a/drivers/net/dsa/microchip/lan937x_dev.c
> > +++ b/drivers/net/dsa/microchip/lan937x_dev.c
> > @@ -386,8 +386,15 @@ static int lan937x_mdio_register(struct
> > ksz_device *dev)
> > 
> >  static int lan937x_switch_init(struct ksz_device *dev)
> >  {
> > +     int ret;
> > +
> >       dev->ds->ops = &lan937x_switch_ops;
> > 
> > +     /* Check device tree */
> > +     ret = lan937x_check_device_id(dev);
> > +     if (ret < 0)
> > +             return ret;
> > +
> 
> Can't this be called from lan937x_spi_probe() directly, why do you
> need
> to go through lan937x_switch_register() first?

lan937x_check_device_id function compares the dev->chip_id with the
lan937x_switch_chip array and populate the some of the parameters of
struct ksz_dev. The dev->chip_id is populated using the dev->dev_ops-
>detect in the ksz_switch_register function. If lan937x_check_device_id
needs to be called in spi_probe, then chip_id has to be identified as
part of spi_probe function. Since ksz_switch_register handles the
identifying the chip_id, checking the device_id is part of switch_init.
 
 if (dev->dev_ops->detect(dev))
             return -EINVAL;
 
 ret = dev->dev_ops->init(dev);
 if (ret)
            return ret;


As per the comment, enable_spi_indirect_access function called twice
https://lore.kernel.org/netdev/20220408232557.b62l3lksotq5vuvm@skbuf/
I have removed the enable_spi_indirect_access in the lan937x_setup
function in v13 patch 6. But it actually failed our regression.
The SPI indirect is required for accessing the Internal phy registers.
We have enabled it in lan937x_init before registering the
mdio_register. We need it for reading the phy id.
And another place enabled in lan937x_setup after lan937x_switch_reset
function. When I removed enabling in setup function, switch_reset
disables the spi indirecting addressing. Because of that further phy
register r/w fails. In Summary, we need to enable spi indirect access
in both the places, one for mdio_register and another after
switch_reset. 

Can I enable it both the places? Kindly suggest. 




> 
> >       dev->port_mask = (1 << dev->port_cnt) - 1;
> > 
> >       dev->ports = devm_kzalloc(dev->dev,