linux-kernel - Re: [PATCH v2 2/5] phy: qcom: Add Qualcomm PCIe PHY

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Message-ID: <CAErSpo42N8YHWjrqUCj0ubqZLt4w-3g=ykPdR8ZMmWaW1GjWDw@mail.gmail.com>
Date:	Wed, 20 May 2015 08:23:32 -0500
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Kishon Vijay Abraham I <kishon@...com>
Cc:	Stanimir Varbanov <svarbanov@...sol.com>,
	Rob Herring <robh+dt@...nel.org>,
	Kumar Gala <galak@...eaurora.org>,
	Mark Rutland <mark.rutland@....com>,
	Grant Likely <grant.likely@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arm <linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Mathieu Olivari <mathieu@...eaurora.org>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: Re: [PATCH v2 2/5] phy: qcom: Add Qualcomm PCIe PHY

On Wed, May 20, 2015 at 8:08 AM, Kishon Vijay Abraham I <kishon@...com> wrote:
> Hi Bjorn,
>
>
> On Wednesday 20 May 2015 04:11 AM, Bjorn Helgaas wrote:
>>
>> On Mon, May 04, 2015 at 06:24:10PM +0300, Stanimir Varbanov wrote:
>>>
>>> On 05/04/2015 05:35 PM, Kishon Vijay Abraham I wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Monday 04 May 2015 06:12 PM, Stanimir Varbanov wrote:
>>>>>
>>>>> Add a PCIe PHY driver used by PCIe host controller driver
>>>>> on Qualcomm SoCs like Snapdragon 805.
>>>>>
>>>>> Signed-off-by: Stanimir Varbanov <svarbanov@...sol.com>
>>>>> ---
>>>>>    drivers/phy/Kconfig         |    9 ++
>>>>>    drivers/phy/Makefile        |    1 +
>>>>>    drivers/phy/phy-qcom-pcie.c |  291
>>>>> +++++++++++++++++++++++++++++++++++++++++++
>>>>
>>>>
>>>> Why do you need a new PHY driver for this? Why not use the existing QCOM
>>>> PHY driver. I can see the registers used here in
>>>> phy-qcom-ufs-qmp-14nm.h?
>>>
>>>
>>> I agree that on first glance there are similarities, but I'm not sure
>>> does the PHYs are the same IP blocks. Or at least they are different
>>> revisions which have too many differences. So trying to combine them
>>> will lead to more code than now.
>>>
>>> Either way I will try to understand how many the differences are.
>>
>>
>> Ping, where are we with this?  Should I wait for something else, or are
>> you
>> convinced there's enough difference to warrant a new PHY driver, Kishon?
>
>
> I'd like to wait to see if Stanimir can use existing driver instead of
> creating a new driver.

OK, I'm waiting for a v3 with either tweaks to the QCOM PHY driver, or
stronger justification as to why that's impossible.  It's hard to
quantify statements like "there are similarities, but there are too
many differences," so you might have to actually attempt a patch for
the QCOM code and we can see how ugly that would turn out to be.

Thanks, Kishon.

Bjorn
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