Messages in this thread | | | Date | Sun, 04 Mar 2007 18:50:18 -0500 | From | Stephen Clark <> | Subject | Re: [PATCH] libata: warn if speed limited due to 40-wire cable (v2) |
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Bill Davidsen wrote:
>Stephen Clark wrote: > > >>Bill Davidsen wrote: >> >> >> >>>Alan Cox wrote: >>> >>> >>> >>> >>>>>it seems broken to manipulate xfer_mask after returning from the >>>>>driver's ->mode_filter hook. >>>>> >>>>>this patch is more than just a speed-limited warning printk, afaics >>>>> >>>>> >>>>> >>>>I actually suggested that order because the only way the printk can be >>>>done correctly is for it to be the very last test made. Since the mode >>>>filter is not told what mode will be used but just subtracts modes that >>>>are not allowed this should be safe. >>>> >>>> >>>> >>>Far better to have a drive which works slowly than one which works >>>unreliably. >>> >>> >>> >>> >>> >>That would be true if the 40 wire detection was 100% accurate! >> >> >The statement is completely correct, even though the detection may not >be. ;-) > >With the current set(s) of patches to do better detection, cable >evaluation should be better. But even if not, a slow system is more >useful than one which doesn't work, crashes because of swap i/o errors, etc. > > > I have had problems with cable detection on my previous laptop and my current laptop. It almost made my systems unusable. On my current laptop I was getting a thruput of a little over 1 mbps instead of the 44 mbps I get with udma set to the correct value. It took hours to upgrade my laptop from fc5 to fc6 because of this mis detection.
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