[PATCH 6/6] ARM: l2x0: Optimise the range based operations

[Shilimkar, Santosh]

> -----Original Message-----
> From: Russell King - ARM Linux [mailto:linux at arm.linux.org.uk]
> Sent: Tuesday, October 05, 2010 2:53 AM
> To: Shilimkar, Santosh
> Cc: linux-arm-kernel at lists.infradead.org; catalin.marinas at arm.com;
> tglx at linutronix.de; linux-omap at vger.kernel.org
> Subject: Re: [PATCH 6/6] ARM: l2x0: Optimise the range based operations
> 
> On Tue, Sep 07, 2010 at 01:27:23PM +0530, Santosh Shilimkar wrote:
> > For the big buffers which are in excess of cache size, the maintaince
> > operations by PA are very slow. For such buffers the maintainace
> > operations can be speeded up by using the WAY based method.
> 
> This causes my Versatile Express to corrupt MMC transfers.  Reverting
> both this and the 'Determine cache size' patches makes it work again.
>
> (Note that just reverting this one doesn't result in a working situation.)
> 
Mostly MMC buffers are smaller than 512KB so the optimization won't
even be invoked.

> Good boot:
> 
> L310 cache controller enabled
> l2x0: 8 ways, CACHE_ID 0x410000c3, AUX_CTRL 0x02460000
> ...
> mmci-pl18x mb:mmci: mmc0: MMCI rev 0 cfg 00 at 0x0000000010005000 irq
> 41,42
> aaci-pl041 mb:aaci: ARM AC'97 Interface at 0x0000000010004000, irq 43,
> fifo 512
> ALSA device list:
>   #0: ARM AC'97 Interface at 0x0000000010004000, irq 43
> TCP cubic registered
> mmc0: host does not support reading read-only switch. assuming write-
> enable.
> mmc0: new SD card at address e624
> mmcblk0: mmc0:e624 SD02G 1.89 GiB
> NET: Registered protocol family 17
> VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 0
>  mmcblk0: p1
> Initalizing network drop monitor service
> Waiting 5sec before mounting root device...
> port 1 high speed
> 
> Bad boot (with just 'Determine cache size' patch applied):
> 
> L310 cache controller enabled
> l2x0: 8 ways, CACHE_ID 0x410000c3, AUX_CTRL 0x02460000, Cache size: 512 KB
> ...
> mmci-pl18x mb:mmci: mmc0: MMCI rev 0 cfg 00 at 0x0000000010005000 irq
> 41,42
> aaci-pl041 mb:aaci: ARM AC'97 Interface at 0x0000000010004000, irq 43,
> fifo 512
> ALSA device list:
>   #0: ARM AC'97 Interface at 0x0000000010004000, irq 43
> mmc0: host does not support reading read-only switch. assuming write-
> enable.
> mmc0: new SD card at address e624
> mmcblk0: mmc0:e624 SD02G 1.89 GiB
> TCP cubic registered
> NET: Registered protocol family 17
> mmcblk0: retrying using single block read
> VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 0
> mmcblk0: error -5 transferring data, sector 0, nr 8, card status 0x900
> Initalizing network drop monitor service
> <random garbage>
> mmcblk0: error -5 transferring data, sector 1, nr 7, card status 0x900
> end_request: I/O error, dev mmcblk0, sector 1
> Buffer I/O error on device mmcblk0, logical block 0
> port 1 high speed
> 
> -5 is -EIO, which is a FIFO overrun error, so somehow these changes are
> causing the CPU or bus accesses to be slower.
I don't see the problem on OMAP MMC.
May be some how additional check is making these operations 
touch slower which lead to the under run.

Will have a look at it again. May for this merge window you can
drop 'Optimise the range based operations' and ''Determine cache size'
patches.

Regards,
Santosh