2.6.24-rc4-mm1 and Very Slow PCMCIA Compact Flash

[Andrew Morton]

On Sat, 08 Dec 2007 20:02:54 -0700 Zan Lynx <zlynx at acm.org> wrote:

> 
> On Sat, 2007-12-08 at 02:07 -0800, Andrew Morton wrote:
> > On Fri, 07 Dec 2007 22:01:33 -0700 Zan Lynx <zlynx at acm.org> wrote:
> > 
> > > 
> > > On Fri, 2007-12-07 at 15:22 -0800, Andrew Morton wrote:
> > > > On Fri, 07 Dec 2007 23:09:43 +0000
> > > > Zan Lynx <zlynx at acm.org> wrote:
> > > [cut] 
> > > > > > > Now with MM kernels 2.6.24 rc1-4 the PCMCIA adapter works again, but I
> > > > > > > only get read rates of 1.6 MB/s.  When it used to work in 2.6.20 I got
> > > > > > > at least 16 MB/s.  The card itself is capable of 30+ in the USB-2
> > > > > > > reader.
> [cut]
> > argh.  OK.  And Linus's current tree is OK, yes?
> > 
> > In which case we should be OK for 2.6.24 and I guess we can hope like heck
> > that the dud patch doesn't leak into mainline.  Hopefully Alan will get
> > some time to look into it before 2.6.25 opens.
> 
> Linus' tree is also broken.
> 
> I tried a Linus 2.6.24-rc4 and it acts the same way, with a very slow
> transfer rate.  

shit

> I also tried 2.6.24-rc4 with the older not-libata PATA drivers and it is
> broken.

squared.

>  dmesg had a line about the CF card detected as hda,
> but /sys/block did not have hda and /dev/hda did not function.

But these drivers did work in earlier kernels, yes? 2.6.20 worked, but
we don't know about intervening kernels.

Can you tell us which version(s)?

> I will try the patches you mentioned

Yes, that won't tell use anything.

> but I think I may also have to
> work backward through kernel versions until I find the last one where
> the PCMCIA hd{a,b,c,d,e} drivers worked.

That would be great - a git-bisect is often ideal. 
http://www.kernel.org/doc/local/git-quick.html has details.