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RE: USB Driver uhci.c legacy mode

From: D, Eshwar (Eshwar)
Subject: RE: USB Driver uhci.c legacy mode
Date: Tue, 27 Jul 2010 10:24:09 +0530

   I would like to contribute for EHCI driver.. Let me know if any space is 
available for me... By the way I already spoke to Ales & Vladimir... 


> -----Original Message-----
> From: address@hidden 
> [mailto:address@hidden
> ] On Behalf Of Aleš Nesrsta
> Sent: Saturday, July 24, 2010 11:45 PM
> To: The development of GNU GRUB
> Subject: Re: USB Driver uhci.c legacy mode
> Hi, I am sorry to be late with answer, unfortunately, I have 
> few time during our school holidays...
> To Your questions, chronologically:
> > how would i surely know that grub usb driver would not work on this 
> > platform?
> None of current USB drivers will work if Your PC is EHCI-only 
> PC. One way how to find it I described before (via lspci). 
> But You have to be sure You have properly set USB part in 
> BIOS (or You should try all possible USB BIOS configurations 
> etc. ...).
> Another way is for example to find detailed specification of 
> Your laptop HW. I tried shortly to find something on Internet 
> but there are specifications like "USB 2.0 compatible" etc. 
> and the same specifications are often used also for 
> controllers which includes OHCI/UHCI USB 1.0 too - so, I am not sure.
> Definitely You can find it by check of HCSPARAMS register of EHCI.
> According EHCI specification, this 32-bit register should be 
> + 08h (USBBASE pointer should be in PCI configuration registers at PCI
> base + 10h).
> Bits 15:12 of HCSPARAMS should be nonzero. If You find zero 
> there, You have EHCI-only controller (without OHCI/UHCI 
> companion controllers) in Your PC, i.e., Your USB controller 
> is currently not directly supported by GRUB :-(
> > jonatan perry wrote:
> > i have another question regarding grub usb ehci support - is such 
> > support under development? is such support are planned to 
> be? what is 
> > the current status?
> Hm, I am not the right person to answer these questions 
> properly, I am not coordinator... Maybe Vladimir Serbinenko 
> will answer it better.
> >From my point of view:
> - Development of EHCI is planned.
> - Current status of EHCI driver development - probably 0%. 
> AFAIK, nobody is currently working on EHCI support. But I 
> could be wrong and it can change at any time.
> I was asked some months ago by Vladimir, if I am interesting 
> also in EHCI. I answered "no" originally - because I thought 
> that all EHCI controllers have also companion OHCI/EHCI 
> controllers and speed of USB
> 1.0/1.1 devices is not critical for GRUB (because it is "only"
> bootloader...).
> I changed point of view from some reasons short time ago. I 
> wanted, at least, find why some devices are not working on my 
> EHCI/UHCI port - it looks like problem is on powering of 
> ports (but UHCI has no power control of its ports - or, at 
> least, it is not written in UHCI specification...). I think 
> that this problem is maybe somewhere in EHCI, so I want to 
> start some experiments with EHCI.
> But:
> - GRUB USB development is currently focused on enhancement 
> and debugging of current USB drivers and related code - for 
> example hot-plugging and hub support. I want to help with 
> these things first before doing something new (and generate 
> new bugs...).
> - EHCI is different and more complex than OHCI/UHCI
> - it looks like I will too busy in next weeks/months. So, if 
> EHCI support will depend only on me, it will take very long 
> time... Maybe somebody else will start development of EHCI 
> driver sooner (or maybe it is started?)...?
> With regards
> Ales
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