BestComm ATA task on MPC52xx

BestComm ATA task on MPC52xx

[Marian Balakowicz]

Hi,

I am working on bringing up a DMA support for ATA controller on MPC52xx
and I am facing problems for which I am not pretty sure what the actual
root cause is.

There was a John Rigby's patch last year, which was based on arch/ppc
and drivers/ide (mpc52xx_ide.c). I use arch/powerpc and adopted to
libata version of mpc52xx_ide.c which is now merged to vanilla and is
called pata_mpc52xx.c. On top of this I have John Rigby's modifications
converted from ide to libata. Problems appear with the first DMA
transfer attempt, which happens during a driver probe when partition
table is read. There shall be a interrupt signaling a transfer end and
the handler (not present in John Rigby's code) should do the transfer
closing. But the interrupt is not received and after the cmd timeouts it
looks like ATA controller registers, BestComm registers, buffer
descriptors and BestComm ATA task variables are unchanged. So, it seems
that for some reason ATA BestComm task did not run/do it's job.

Did anyone had any success with ATA DMA on 52xx? Or maybe hear about
newer version of the ATA BestComm task, or some useful ways of debugging
BestComm stuff? I am planning to post my working code but need a day or
two to clean it up a little.

Thanks,
Marian

Re: BestComm ATA task on MPC52xx

[Matt Sealey]

Which chip revision are you using?

-- 
Matt Sealey <matt@genesi-usa.com>
Genesi, Manager, Developer Relations

Marian Balakowicz wrote:
> Hi,
> 
> I am working on bringing up a DMA support for ATA controller on MPC52xx
> and I am facing problems for which I am not pretty sure what the actual
> root cause is.
> 
> There was a John Rigby's patch last year, which was based on arch/ppc
> and drivers/ide (mpc52xx_ide.c). I use arch/powerpc and adopted to
> libata version of mpc52xx_ide.c which is now merged to vanilla and is
> called pata_mpc52xx.c. On top of this I have John Rigby's modifications
> converted from ide to libata. Problems appear with the first DMA
> transfer attempt, which happens during a driver probe when partition
> table is read. There shall be a interrupt signaling a transfer end and
> the handler (not present in John Rigby's code) should do the transfer
> closing. But the interrupt is not received and after the cmd timeouts it
> looks like ATA controller registers, BestComm registers, buffer
> descriptors and BestComm ATA task variables are unchanged. So, it seems
> that for some reason ATA BestComm task did not run/do it's job.
> 
> Did anyone had any success with ATA DMA on 52xx? Or maybe hear about
> newer version of the ATA BestComm task, or some useful ways of debugging
> BestComm stuff? I am planning to post my working code but need a day or
> two to clean it up a little.
> 
> Thanks,
> Marian
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev

Re: BestComm ATA task on MPC52xx

[Marian Balakowicz]

Matt Sealey wrote:
> Which chip revision are you using?

Here's the configuration:

CPU:   MPC5200B v2.2, Core v1.4 at 350 MHz
       Bus 100 MHz, IPB 100 MHz, PCI 25 MHz

The board uses not quite typical 100 MHz bus clock, for which I don't
have a optimized ATA DMA timing parameters yet, instead, temporarily I
use too wasteful 132MHz settings.

Marian