Re: [PATCH] mac_esp: fix PIO mode

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From: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
Date: Mon, 23 Nov 2009 14:57:42 +1100 (EST)


The mac_esp PIO algorithm no longer works in 2.6.31 and crashes my Centris 
660av. So here's a better one.

One of the SCSI drives I tested still doesn't like the PIO mode and fails 
with "esp: esp0: Reconnect IRQ2 timeout" (the same drive works fine in 
PDMA mode).

This failure happens when esp_reconnect_with_tag() tries to read in two 
tag bytes but the chip only provides one (0x20). I don't know what causes 
this. I decided not to waste any more time trying to fix it because the 
best solution is to rip out the PIO mode altogether and use the DMA 
engine.

Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>

Can you explain why the esp_slave_configure() part of your patch
is necessary?

Index: linux-2.6.31/drivers/scsi/esp_scsi.c
===================================================================
--- linux-2.6.31.orig/drivers/scsi/esp_scsi.c	2009-11-23 12:52:45.000000000 +1100
+++ linux-2.6.31/drivers/scsi/esp_scsi.c	2009-11-23 12:53:30.000000000 +1100
@@ -2405,12 +2405,6 @@ static int esp_slave_configure(struct sc
 	struct esp_target_data *tp = &esp->target[dev->id];
 	int goal_tags, queue_depth;
 
-	if (esp->flags & ESP_FLAG_DISABLE_SYNC) {
-		/* Bypass async domain validation */
-		dev->ppr  = 0;
-		dev->sdtr = 0;
-	}
-
 	goal_tags = 0;
 
 	if (dev->tagged_supported) {
@@ -2433,6 +2427,11 @@ static int esp_slave_configure(struct sc
 	}
 	tp->flags |= ESP_TGT_DISCONNECT;
 
+	if (esp->flags & ESP_FLAG_DISABLE_SYNC) {
+		dev->wdtr = spi_support_wide(dev->sdev_target) = 0;
+		dev->sdtr = spi_support_sync(dev->sdev_target) = 0;
+	}
+
 	if (!spi_initial_dv(dev->sdev_target))
 		spi_dv_device(dev);
 

That part...

Thanks.
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