Re: [PATCH v2 05/06] input synaptics-rmi4: Add firmware update support

[Christopher Heiny <cheiny@synaptics.com>]

On 08/06/2014 11:42 PM, Dmitry Torokhov wrote:
> On Wed, Aug 06, 2014 at 04:28:26PM -0700, Christopher Heiny wrote:
>> [I sent this last Thursday, but it never showed up on the input
>> list. I'm assuming nobody else saw it.]
>>
>>
>> On 07/31/2014 02:58 PM, Dmitry Torokhov wrote:
>>> On Thu, Jul 31, 2014 at 02:43:47PM -0700, Christopher Heiny wrote:
>>>> On 07/31/2014 02:19 PM, Dmitry Torokhov wrote:
>>>>> On Thu, Jul 31, 2014 at 02:00:14PM -0700, Christopher Heiny wrote:
>>>>>>> On 07/31/2014 10:53 AM, Dmitry Torokhov wrote:
>>>>>>>>> Hi Christopher,
>>>>>>>>>
>>>>>>>>> On Wed, Mar 12, 2014 at 06:53:56PM -0700, Christopher Heiny wrote:
>>>>>>>>>>> Add support for updating firmware on RMI4 devices with V5 bootloader.
>>>>>>>>>
>>>>>>>>> I am wondering why F34 is not following the staindard RMI function
>>>>>>>>> implementation. By that I mean that it does not declare itself as struct
>>>>>>>>> rmi_function_handler and does not rely on RMI core to bind itself to the device
>>>>>>>>> if device supports it.
>>>>>>>
>>>>>>> Hi Dmitry,
>>>>>>>
>>>>>>> We originally had an F34 implementation that followed the RMI4
>>>>>>> function standard and exposed most of the basic F34 operations via
>>>>>>> sysfs. However, we got feedback (both on LKML and offline) (a)
>>>>>>> recommending to use request_firmware, and (b) improve reflash times
>>>>>>> while (c) reducing impact on boot time, and (d) "get rid of all that
>>>>>>> sysfs crap" (paraphrased, but close to it).
>>>>>>>
>>>>>>> So after looking at how some other drivers use request_firmware, we
>>>>>>> came up with the current approach.  Switching to request_firmware
>>>>>>> definitely sped up the reflash times!  Including a check to see if
>>>>>>> firmware update is required before setting up the RMI4
>>>>>>> sensor/function structures also significantly reduced boot times.
>>>>>
>>>>> I am not suggesting you stop using request-firmware or introduce
>>>>> bazillion of new sysfs attributes. I just wondered why you have manual
>>>>> "binding" of F34 functionality instead of standrad RMI4 function
>>>>> binding, liek you do for F01, F11 and so forth.
>>>>
>>>> Sorry!  My answer wasn't very clear on that part, was it?
>>>>
>>>> The manual binding gets the reflash (if required) done very early in
>>>> the boot/probe process.  This eliminates the need to set up the
>>>> whole sensor + functions structure, tear it down in order to
>>>> reflash, and then build it all back up again.  It is felt that the
>>>> time savings is significant, especially on highly featured products.
>>>
>>> I am sorry but I have hard time accepting this argument. How often do
>>> you reflash devices during normal operation and how long does it take to
>>> initialize the device compared to getting entire userspace up and
>>> running to be able to actually supply or serve flash data (even without
>>> using usermode helper to flash you need filesystem with the firmware to
>>> be mounted)?
>>
>> That was my argument exactly, but that was the direction we were
>> pushed.  I'd much rather implement it as we discussed offline
>> earlier this week.  If you were to say: "I'm sorry, but this simply
>> can't be merged as it stands." you wouldn't get any argument from me
>> on technical grounds. There might be people who will argue about the
>> additional calendar time it would take to restructure it, though.
>
> OK, then I will just say this: "I'm sorry, but this simply can't be merged as
> it stands."
>
> Now, I am talking about mainline here, I am fairly certain we can resolve
> scheduling issues between what you currently have and what is needed in the
> end.

OK.  The question on our end becomes - can we accept the current 
implementation as a baseline while we rework the implementation to use a 
conformant F34 implementation?  Our rough estimation is that this will 
be ready around the end of this month or early next month.

					Thanks,
						Chris