linux-kernel - Re: [PATCH v2 1/5] phy: berlin-sata: Move PHY

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Date:	Thu, 30 Oct 2014 10:57:03 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	<balbi@...com>
CC:	Antoine Ténart 
	<antoine.tenart@...e-electrons.com>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/5] phy: berlin-sata: Move PHY_BASE into private data
 struct



On Tuesday 28 October 2014 12:02 AM, Sebastian Hesselbarth wrote:
> On 10/27/2014 01:27 PM, Kishon Vijay Abraham I wrote:
>> On Saturday 25 October 2014 01:55 AM, Felipe Balbi wrote:
>>> On Fri, Oct 24, 2014 at 10:14:55PM +0200, Sebastian Hesselbarth wrote:
>>>> On 21.10.2014 11:40, Sebastian Hesselbarth wrote:
>>>>> On 10/21/2014 11:33 AM, Kishon Vijay Abraham I wrote:
>>>>>> On Tuesday 21 October 2014 02:37 PM, Sebastian Hesselbarth wrote:
>>>>>>> Currently, Berlin SATA PHY driver assumes PHY_BASE address being
>>>>>>> constant. While this PHY_BASE is correct for BG2Q, older BG2 PHY_BASE
>>>>>>> is different. Prepare the driver for BG2 support by moving the phy_base
>>>>>>> into private driver data.
>>>>>>>
>>>>>>> Acked-by: Antoine Ténart <antoine.tenart@...e-electrons.com>
>>>>>>> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
>>>>> ...
>>>>>>> ---
>>>>>>>   drivers/phy/phy-berlin-sata.c | 42
>>>>>>> ++++++++++++++++++++++++++++--------------
>>>>>>>   1 file changed, 28 insertions(+), 14 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/phy/phy-berlin-sata.c
>>>>>>> b/drivers/phy/phy-berlin-sata.c
>>>>>>> index 69ced52d72aa..9682b0f66177 100644
>>>>>>> --- a/drivers/phy/phy-berlin-sata.c
>>>>>>> +++ b/drivers/phy/phy-berlin-sata.c
>>>>>>> @@ -30,7 +30,7 @@
>>>>>>>   #define MBUS_WRITE_REQUEST_SIZE_128    (BIT(2) << 16)
>>>>>>>   #define MBUS_READ_REQUEST_SIZE_128    (BIT(2) << 19)
>>>>>>>
>>>>>>> -#define PHY_BASE        0x200
>>>>>>> +#define BG2Q_PHY_BASE        0x200
>>>>> [...]
>>>>>>> +static u32 bg2q_sata_phy_base = BG2Q_PHY_BASE;
>>>>>>> +
>>>>>>> +static const struct of_device_id phy_berlin_sata_of_match[] = {
>>>>>>> +    {
>>>>>>> +        .compatible = "marvell,berlin2q-sata-phy",
>>>>>>> +        .data = &bg2q_sata_phy_base,
>>>>>>
>>>>>> Can't the base directly come from dt?
>>>>>
>>>>> You are suggesting a "marvell,phy-base-address" property, right?
>>>>> I have no strong opinion about it, I accept your call (or DT maintainer
>>>>> ones).
>>>>
>>>> I still have the DT patches for BG2Q queued up for v3.19 (I missed the
>>>> arm-soc merge window for v3.18). That means, there has been no release
>>>> with the phy binding used and I can rework a little more.
>>>>
>>>> Can you please confirm that you want a DT property for the phy base address,
>>>> e.g. marvell,phy-base-address = <{0x200,0x80}> ?
>>>>
>>>> If so, I'd also rename the compatible from berlin2q-sata-phy to more
>>>> generic berlin-sata-phy.
>>>
>>> I think what Kishon is asking, is why this 0x200 offset isn't already on
>>> reg. so that instead of, e.g.:
>>>
>>>     reg = <0x40000000 0x1000>;
>>>
>>> you would have:
>>>
>>>     reg = <0x40000200 0x1000>;
>>
>> I had something similar to what Sebastian suggested in mind. I think phy_base
>> is used for a different reason and can't be directly used in 'reg'.
> 
> Kishon,
> 
> thanks for the clarification. While the extra marvell,phy-base-address
> property basically works and I agree with it, I may have some
> _potential_ draw-backs:
> 
> The Marvell BSP code (which I have no clue _why_ it does what it does
> or if it is required) has some magic writes to "improve" serial signal
> quality. I left them out as my HDD was detected with and without them.
> 
> Now, if we find that they are required, we have to find a way to make
> the PHY driver know about the PHY revision. We'd usually add a
> different compatible and deal with it accordingly.
> 
> So, not adding the compatible now _may_ just postpone a follow-up patch
> for the different PHY setup of BG2 and render the new phy_base property
> basically useless.
> 
> If you are just unhappy with the "static u32 bg2q_sata_phy_base"
> assigned to of_device_id.data, I can convert that to Felipe's proposal.

Either way is fine with me.

Thanks
Kishon
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