Hello Greg,
Tuesday, November 16, 2010, 6:02:30 PM, you wrote:
> On Tue, Nov 16, 2010 at 05:41:46PM +0100, Sander Eikelenboom wrote:
>> Tuesday, November 16, 2010, 5:33:48 PM, you wrote:
>>
>> > On Tue, Nov 16, 2010 at 05:29:15PM +0100, Clemens Ladisch wrote:
>> >> Greg KH wrote:
>> >> > On Tue, Nov 16, 2010 at 05:06:31PM +0100, Clemens Ladisch wrote:
>> >> > > But would you accept patches that make the drivers test, when attaching,
>> >> > > whether the MSI interrupt actually works, and fall back to INTx
>> >> > > otherwise? This would break only for devices that blow up completely
>> >> > > when configured for MSI; I don't know if or how many of those exist.
>> >> >
>> >> > That would be better, but again, is this all really worth it? What
>> >> > benifits will MSI for usb controllers accomplish?
>> >>
>> >> On many chipsets, the onboard USB controllers all share the same
>> >> interrupt, or share their interrupts with lots of other devices.
>> >> Using MSI allows the handlers to run concurrently on different CPU
>> >> cores, and might protect other devices against interrupt storms if
>> >> a device or driver fails.
>>
>> > But is that a failure that anyone has ever reported?
>>
>> > I don't see the benefit of adding this and dealing with the fallout of
>> > lots of broken systems that previously were working just fine.
>>
>> > Do you?
>>
>> > greg k-h
>>
>> I guess that's why Clemens put it as a module option in the first place ?
> Module options suck. Seriously, they are a pain and no one uses them.
>> Another way could be to use the fallback scenario, and try it first in
>> linux-next for a while, if that still gives a lot of problems in
>> practice, revert and make it a module option ?
> No, linux-next does not get very wide testing at all for something like
> this.
> Again, I fail to see any real benifit for this change, and lots of
> problems that can occur.
OK, perhaps that will change one day .. so than just for the record .. the patches seem to work fine so far with moschip 9990:
0d:00.5 USB Controller: NetMos Technology Device 9990 (prog-if 20 [EHCI])
Subsystem: Device a000:4000
0d:00.6 USB Controller: NetMos Technology Device 9990 (prog-if 10 [OHCI])
Subsystem: Device a000:4000
--
Sander
> thanks,
> greg k-h
--
Best regards,
Sander mailto:linux@xxxxxxxxxxxxxx
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