Re: [PATCH 2.6.19 2/3] sata_promise: new EH conversion

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

On Sun, 03 Dec 2006 22:00:42 +0900, Tejun Heo wrote:
>Mikael Pettersson wrote:
>> +}
>> +
>> +static void pdc_error_handler(struct ata_port *ap)
>> +{
>> +	struct ata_eh_context *ehc = &ap->eh_context;
>> +	ata_reset_fn_t hardreset;
>> +
>> +	/* stop DMA, mask IRQ, don't clobber anything else */
>> +	ata_eh_freeze_port(ap);
>
>Don't freeze port unconditionally.  You'll end up hardresetting on every
>error.  Just make sure DMA engine is stopped and the controller is in a
>sane state.  If that fails, then, the port should be frozen.

I'm looking into this now, but so far it seems only a reset
(what Promise calls software reset, I don't know if libata
considers it a soft or hard reset) of the ATA channel will do.

>> +	hardreset = NULL;
>> +	if (sata_scr_valid(ap)) {
>> +		ehc->i.action |= ATA_EH_HARDRESET;
>
>Why always force HARDRESET?

I based that on sata_sil24:

	if (sil24_init_port(ap)) {
		ata_eh_freeze_port(ap);
		ehc->i.action |= ATA_EH_HARDRESET;
	}

I interpreted the ATA_EH_HARDRESET as being required due to
the ata_eh_freeze_port(), but perhaps it's only there because
sil24_init_port() returned failure?

A different issue, but of practical importance, is which
libata branch I should base the EH conversion on: #upstream
or #ALL? Andrew Morton's -mm kernels include the ALL patches,
but they in turn include the promise-sata-pata patches, and
there is a conflict between the PATA patch and the EH conversion.
Currently my EH conversion is based on #upstream, and I've ported
the PATA patch to apply on top of it.

/Mikael
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