linux-kernel - Re: similar files: fusbh200-hcd.c and fotg210-hcd.c

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Message-ID: <CA+MoWDqMtoPVzc7ra0oc-FgekTkKQsEuDK1F6nPnur2uCD84gA@mail.gmail.com>
Date:	Fri, 25 Sep 2015 15:04:55 +0200
From:	Peter Senna Tschudin <peter.senna@...il.com>
To:	Felipe Balbi <balbi@...com>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Masanari Iida <standby24x7@...il.com>, pmladek@...e.cz,
	linux-usb@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: similar files: fusbh200-hcd.c and fotg210-hcd.c

On Tue, Sep 15, 2015 at 6:50 PM, Felipe Balbi <balbi@...com> wrote:
> Hi,
>
> On Tue, Sep 15, 2015 at 06:41:55PM +0200, Peter Senna Tschudin wrote:
>> On Tue, Sep 15, 2015 at 4:33 PM, Felipe Balbi <balbi@...com> wrote:
>> > On Mon, Sep 14, 2015 at 07:50:02PM +0200, Peter Senna Tschudin wrote:
>> >> On Mon, Sep 14, 2015 at 5:01 PM, Felipe Balbi <balbi@...com> wrote:
>> >> > On Sat, Sep 12, 2015 at 03:14:50PM +0200, Peter Senna Tschudin wrote:
>> >> >> >> Should these files be consolidated? And if so how?
>> >> >> > if you can find an easy way, that would be a very, very welcome patch.
>> >> >>
>> >> >> Is the ideal solution to consolidate both fusbh200-hcd.c and
>> >> >> fotg210-hcd.c in a single module? If this is the case, how to detect
>> >> >> at run time which version of the hw is present? Both are registered as
>> >> >
>> >> > does it matter ? If they work the same way, why does it matter which
>> >> > one's running?
>> >>
>> >> I may be missing something simple, but based on a 2 page product
>> >> brief, fotg210 has more resources like memory. So even if the .c files
>> >> are _very_ similar, there are some configuration parameters that
>> >> differ, for example:
>> >>
>> >> fusbh200.h:
>> >> #define BMCSR_VBUS_OFF (1<<4)
>> >> #define BMCSR_INT_POLARITY (1<<3)
>> >>
>> >> fotg210.h:
>> >> #define OTGCSR_A_BUS_DROP (1 << 5)
>> >> #define OTGCSR_A_BUS_REQ (1 << 4)
>> >
>> > Can you detect that in runtime ? If you can, detect it. If you can't use
>> > different platform_device_id.
>> >
>> >> >> notebook (hp elitebook 840), and on a VM, even if neither has the hw
>> >> >> ($ sudo modprobe fusbh200-hcd). The module loads with the warning
>> >> >> "fusbh200_hcd should always be loaded before uhci_hcd and ohci_hcd,
>> >> >> not after". On another workstation running ubuntu, I could load both
>> >> >> modules at the same time, producing the same warning for each module.
>> >> >> Should the module load if the device is not present?
>> >> >>
>> >> >> Other solution for consolidation would be to create a common_code.c,
>> >> >> keeping both fusbh200-hcd.c and fotg210-hcd.c only with the code that
>> >> >> differ. Is this better than what is there now?
>> >> >>
>> >> >> Other ideas?
>> >> >
>> >> > just combine them :-p Use platform_device_id to differentiate.
>>
>> Can you check the f2xx branch at:
>>
>> git@...hub.com:petersenna/linux.git
>>
>> And tell me if this is the way to go for the consolidation of the two
>> drivers? I started with the newest driver, did code cleanup, and
>> started filling the new driver with parameters from the older
>> FUSBH200. At the moment it compiles for x86 and probably still works
>> for FOTG210 devices. A concrete question I have is if should I keep
>> making many patches for the consolidation or should I do a single big
>> patch with all changes? Comments are welcome.
>
> it's best to just send patches. Also, you gave me an ssh URL which I
> can't use because I don't have write access to your tree (and I don't
> want to have it).
Sorry for that, my goal was not to send more than 10 patches just to
illustrate my questions. It looked more efficient to make the patches
available for analysis instead of spamming you.

I sent a RFC patch series to the list, it would help me a lot if you
can give me some feedback, mainly hints about the questions on the
cover letter.

Thank you for the feedback Sergei Shtylyov! I'll include your
suggestions in the next series.


>
> --
> balbi



-- 
Peter
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