linux-kernel - Re: [PATCH 2/3] msm: Peripheral Image Loader (PIL) driver

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Message-ID: <4D8105F5.1030307@codeaurora.org>
Date:	Wed, 16 Mar 2011 11:48:21 -0700
From:	Saravana Kannan <skannan@...eaurora.org>
To:	David Brown <davidb@...eaurora.org>
CC:	Daniel Walker <dwalker@...o99.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3] msm: Peripheral Image Loader (PIL) driver

On 03/16/2011 11:40 AM, David Brown wrote:
> On Wed, Mar 16 2011, Daniel Walker wrote:
>
>> On Wed, 2011-03-09 at 20:44 -0800, Stephen Boyd wrote:
>>> On 8660, the modem, dsp, and sensors peripherals require their
>>> firmware to be loaded into memory before they can be properly
>>> taken out of reset.
>>>
>>> Drivers are expected to call pil_get() when they wish to load a
>>> peripheral. This will initiate multiple firmware_request()s for
>>> the metadata and image blobs for a peripheral. Once the image has
>>> been loaded into memory, it is validated and brought out of reset
>>> via the peripheral reset driver.
>>
>> Why can't this be part of the generic firmware request API ?
>
> Can you clarify what you mean by this?  The firmware request API is used
> to get the firmware itself, which this code uses.  This code is what
> manages making those calls for the various MSM peripherals that require
> firmware.
>
>>> diff --git a/arch/arm/mach-msm/Kconfig b/arch/arm/mach-msm/Kconfig
>>> index 997c5bd..25b73b0 100644
>>> --- a/arch/arm/mach-msm/Kconfig
>>> +++ b/arch/arm/mach-msm/Kconfig
>>> @@ -210,4 +210,17 @@ config IOMMU_API
>>>
>>>   config MSM_SCM
>>>          bool
>>> +
>>> +config MSM_PIL
>>> +       bool "Peripheral image loading (PIL)"
>>> +       select FW_LOADER
>>> +       select MSM_SCM
>>> +       depends on ARCH_MSM8X60
>>> +       help
>>> +         Some peripherals need to be loaded into memory before they
>>> can be
>>> +         brought out of reset.
>>> +
>>> +         Say yes to support these devices.
>>> +
>>> +
>>
>> You shouldn't be adding anything like this to the Kconfig. To me if you
>> add stuff like this it's a big red flag.
>
> Can you clarify what you mean "stuff like this".
>
> It seems to me that this option should be selected by the drivers that
> need it, since it doesn't make sense to have this if there are no
> drivers that need it, and it is required when those drivers are
> included.
>
> I do think there are valid hardware configurations that don't have any
> peripherals needing firmware, and would think that those should be able
> to avoid requiring the code to manage that.  Saravana/Stephen can
> clarify that, though.

Correct. There are plenty of Qualcomm SoCs that don't need this driver. 
There are also valid 8660 configurations that would not need this.

Thanks,
Saravana

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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