netdev - Re: [PATCH net-next v2 2/3] net: macb: Added ZynqMP-specific initialization

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Message-ID: <1624a3d8-0986-8931-264f-3b9d1f1ca5fd@microchip.com>
Date:   Wed, 26 Jan 2022 07:45:10 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <michal.simek@...inx.com>, <robert.hancock@...ian.com>,
        <netdev@...r.kernel.org>
CC:     <davem@...emloft.net>, <kuba@...nel.org>, <robh+dt@...nel.org>,
        <Nicolas.Ferre@...rochip.com>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH net-next v2 2/3] net: macb: Added ZynqMP-specific
 initialization

On 26.01.2022 09:30, Michal Simek wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
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> 
> On 1/25/22 18:05, Robert Hancock wrote:
>> The GEM controllers on ZynqMP were missing some initialization steps which
>> are required in some cases when using SGMII mode, which uses the PS-GTR
>> transceivers managed by the phy-zynqmp driver.
>>
>> The GEM core appears to need a hardware-level reset in order to work
>> properly in SGMII mode in cases where the GT reference clock was not
>> present at initial power-on. This can be done using a reset mapped to
>> the zynqmp-reset driver in the device tree.
>>
>> Also, when in SGMII mode, the GEM driver needs to ensure the PHY is
>> initialized and powered on when it is initializing.
>>
>> Signed-off-by: Robert Hancock <robert.hancock@...ian.com>
>> ---
>>   drivers/net/ethernet/cadence/macb_main.c | 48 +++++++++++++++++++++++-
>>   1 file changed, 47 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/cadence/macb_main.c
>> b/drivers/net/ethernet/cadence/macb_main.c
>> index a363da928e8b..80882908a68f 100644
>> --- a/drivers/net/ethernet/cadence/macb_main.c
>> +++ b/drivers/net/ethernet/cadence/macb_main.c
>> @@ -34,7 +34,9 @@
>>   #include <linux/udp.h>
>>   #include <linux/tcp.h>
>>   #include <linux/iopoll.h>
>> +#include <linux/phy/phy.h>
>>   #include <linux/pm_runtime.h>
>> +#include <linux/reset.h>
>>   #include "macb.h"
>>
>>   /* This structure is only used for MACB on SiFive FU540 devices */
>> @@ -4455,6 +4457,50 @@ static int fu540_c000_init(struct platform_device
>> *pdev)
>>       return macb_init(pdev);
>>   }
>>
>> +static int zynqmp_init(struct platform_device *pdev)
>> +{
>> +     struct net_device *dev = platform_get_drvdata(pdev);
>> +     struct macb *bp = netdev_priv(dev);
>> +     int ret;
>> +
>> +     if (bp->phy_interface == PHY_INTERFACE_MODE_SGMII) {
>> +             /* Ensure PS-GTR PHY device used in SGMII mode is ready */
>> +             struct phy *sgmii_phy = devm_phy_get(&pdev->dev, "sgmii-phy");
>> +
>> +             if (IS_ERR(sgmii_phy)) {
>> +                     ret = PTR_ERR(sgmii_phy);
>> +                     dev_err_probe(&pdev->dev, ret,
>> +                                   "failed to get PS-GTR PHY\n");
>> +                     return ret;
>> +             }
>> +
>> +             ret = phy_init(sgmii_phy);
>> +             if (ret) {
>> +                     dev_err(&pdev->dev, "failed to init PS-GTR PHY: %d\n",
>> +                             ret);
>> +                     return ret;
>> +             }
> 
> I think reset below should be here to follow correct startup sequence.

If that's the case is the functionality still kept if moving phy_power_on()
in macb_open() and the correspondent phy_power_off() in macb_close() ?

Also, Robert, please handle the error path in this function (with calls to
phy_exit(), phy_power_off()) and PHY handling in macb_remove().

Thank you,
Claudiu Beznea

> 
> Thanks,
> Michal
> 
> 
>> +
>> +             ret = phy_power_on(sgmii_phy);
>> +             if (ret) {
>> +                     dev_err(&pdev->dev, "failed to power on PS-GTR PHY:
>> %d\n",
>> +                             ret);
>> +                     return ret;
>> +             }
>> +     }
>> +
>> +     /* Fully reset GEM controller at hardware level using zynqmp-reset
>> driver,
>> +      * if mapped in device tree.
>> +      */
>> +     ret = device_reset_optional(&pdev->dev);
>> +     if (ret) {
>> +             dev_err_probe(&pdev->dev, ret, "failed to reset controller");
>> +             return ret;
>> +     }
>> +
>> +     return macb_init(pdev);
>> +}
>> +
>>   static const struct macb_usrio_config sama7g5_usrio = {
>>       .mii = 0,
>>       .rmii = 1,
>> @@ -4550,7 +4596,7 @@ static const struct macb_config zynqmp_config = {
>>                       MACB_CAPS_GEM_HAS_PTP | MACB_CAPS_BD_RD_PREFETCH,
>>       .dma_burst_length = 16,
>>       .clk_init = macb_clk_init,
>> -     .init = macb_init,
>> +     .init = zynqmp_init,
>>       .jumbo_max_len = 10240,
>>       .usrio = &macb_default_usrio,
>>   };