linux-kernel - Re: [PATCH] phy: bcm-ns-usb3: split all writes into reg & val pairs

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Message-ID: <de0d0714-0be2-5050-af8b-d1d9d2843ef1@ti.com>
Date:   Thu, 6 Apr 2017 15:47:11 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Rafał Miłecki <zajec5@...il.com>
CC:     Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@...adcom.com>,
        Jon Mason <jonmason@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <bcm-kernel-feedback-list@...adcom.com>,
        <linux-kernel@...r.kernel.org>,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH] phy: bcm-ns-usb3: split all writes into reg & val pairs



On Wednesday 05 April 2017 04:22 PM, Rafał Miłecki wrote:
> On 04/05/2017 12:10 PM, Kishon Vijay Abraham I wrote:
>> On Sunday 02 April 2017 10:25 PM, Rafał Miłecki wrote:
>>> From: Rafał Miłecki <rafal@...ecki.pl>
>>>
>>> So far all the PHY initialization was implemented using some totally
>>> magic values. There was some pattern there but it wasn't clear what is
>>> it about.
>>>
>>> Thanks to the patch submitted by Broadcom:
>>> [PATCH 5/6] phy: Add USB3 PHY support for Broadcom NSP SoC
>>> and the upstream "iproc-mdio" driver we now know there is a MDIO bus
>>> underneath with PHY(s) and their registers.
>>>
>>> It allows us to clean the driver a bit by making all these values less
>>> magical. The next step is switching to using a proper MDIO layer.
>>>
>>> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
>>> ---
>>>  drivers/phy/phy-bcm-ns-usb3.c | 69 ++++++++++++++++++++++++++++++-------------
>>>  1 file changed, 49 insertions(+), 20 deletions(-)
>>>
>>> diff --git a/drivers/phy/phy-bcm-ns-usb3.c b/drivers/phy/phy-bcm-ns-usb3.c
>>> index f420fa4bebfc..22b5e7047fa6 100644
>>> --- a/drivers/phy/phy-bcm-ns-usb3.c
>>> +++ b/drivers/phy/phy-bcm-ns-usb3.c
>>> @@ -2,6 +2,7 @@
>>>   * Broadcom Northstar USB 3.0 PHY Driver
>>>   *
>>>   * Copyright (C) 2016 Rafał Miłecki <rafal@...ecki.pl>
>>> + * Copyright (C) 2016 Broadcom
>>>   *
>>>   * All magic values used for initialization (and related comments) were
>>> obtained
>>>   * from Broadcom's SDK:
>>> @@ -23,6 +24,23 @@
>>>
>>>  #define BCM_NS_USB3_MII_MNG_TIMEOUT_US    1000    /* usecs */
>>>
>>> +#define BCM_NS_USB3_PHY_BASE_ADDR_REG    0x1f
>>> +#define BCM_NS_USB3_PHY_PLL30_BLOCK    0x8000
>>> +#define BCM_NS_USB3_PHY_TX_PMD_BLOCK    0x8040
>>> +#define BCM_NS_USB3_PHY_PIPE_BLOCK    0x8060
>>> +
>>> +/* Registers of PLL30 block */
>>> +#define BCM_NS_USB3_PLL_CONTROL        0x01
>>> +#define BCM_NS_USB3_PLLA_CONTROL0    0x0a
>>> +#define BCM_NS_USB3_PLLA_CONTROL1    0x0b
>>> +
>>> +/* Registers of TX PMD block */
>>> +#define BCM_NS_USB3_TX_PMD_CONTROL1    0x01
>>> +
>>> +/* Registers of PIPE block */
>>> +#define BCM_NS_USB3_LFPS_CMP        0x02
>>> +#define BCM_NS_USB3_LFPS_DEGLITCH    0x03
>>> +
>>>  enum bcm_ns_family {
>>>      BCM_NS_UNKNOWN,
>>>      BCM_NS_AX,
>>> @@ -76,8 +94,10 @@ static inline int bcm_ns_usb3_mii_mng_wait_idle(struct
>>> bcm_ns_usb3 *usb3)
>>>                      usecs_to_jiffies(BCM_NS_USB3_MII_MNG_TIMEOUT_US));
>>>  }
>>>
>>> -static int bcm_ns_usb3_mii_mng_write32(struct bcm_ns_usb3 *usb3, u32 value)
>>> +static int bcm_ns_usb3_mdio_phy_write(struct bcm_ns_usb3 *usb3, u16 reg,
>>> +                      u16 value)
>>>  {
>>> +    u32 tmp = 0;
>>>      int err;
>>>
>>>      err = bcm_ns_usb3_mii_mng_wait_idle(usb3);
>>> @@ -86,7 +106,11 @@ static int bcm_ns_usb3_mii_mng_write32(struct
>>> bcm_ns_usb3 *usb3, u32 value)
>>>          return err;
>>>      }
>>>
>>> -    writel(value, usb3->ccb_mii + BCMA_CCB_MII_MNG_CMD_DATA);
>>> +    /* TODO: Use a proper MDIO bus layer */
>>
>> Instead of using this intermediate patch, can we directly convert this to
>> mdio_driver or you see issues with converting it?
> 
> This is a bit more complex task with some possible issues to consider:
> 1) Backward compatibility - should we still support old DTB files?
> 2) Support for PHY DT node put in MDIO bus node - it requires reg = <phy num>;
> which is in conflict with current "reg" usage
> 3) Support for different reset reg - Northstar+ uses a different one - we'll
> probably need a syscon
> 4) My limited time (sadly)

Er..
> 
> The good point of this patch is that all changes made in:
> bcm_ns_usb3_phy_init_ns_ax
> bcm_ns_usb3_phy_init_ns_bx
> will survive, so we're not going to change all the code back and forth.
> 
> If that's acceptable for you, I'd prefer to handle this with smaller patches.

All right. I'll merge the patch as it is now.

Thanks
Kishon