Re: PATCH: [2.4.21-pre3] Fix for Promise PIO Lockup

[Mikael Pettersson <mikpe@csd.uu.se>]

Ross Biro writes:
 > Newer kernels will lock up when a drive command (SMART, hdparm -I, etc.) 
 > is issued to a drive connected to a Promise 20265 or 20267 controller 
 > while the controller is in DMA mode.  The problem appears to be that 
 > tune_chipset incorrectly clears the high PIO bit thinking that it is a 
 > "PIO force on" bit.  The documentation I have access to does not seem to 
 > mention a PIO force bit.  Not changing that bit seems to fix the problem 
 > with drive commands on a promise controller.
 > 
 > The documentation I have also says the values for the TB and TC 
 > variables should be the same for all UDMA modes and they are not. 
 >  However the driver seems to work anyway, so I left them the way they are.
 > 
 > To reproduce this problem make sure your drive is set to a DMA mode, eg 
 > hdparm -X 67 and then issue a drive command, e.g. hdparm -I.

I have tried to reproduce this problem according to your description
above, but neither my 20269 (with "new" driver) nor my 20267 (with
"old" driver) hangs. I checked with kernels 2.5.58 and 2.4.21-pre3.

Maybe something else is needed for the hang to occur?

/Mikael