[PATCH v3] ata: pata_at91.c bugfix for high master clock

From: Igor Plyatov
Date: Mon Mar 28 2011 - 08:00:15 EST


The AT91SAM9 microcontrollers with master clock higher then 105 MHz
and PIO0, have overflow of the NCS_RD_PULSE value in the MSB. This
lead to "NCS_RD_PULSE" pulse longer then "NRD_CYCLE" pulse and driver
does not detect ATA device.

Signed-off-by: Igor Plyatov <plyatov@xxxxxxxxx>
---
drivers/ata/pata_at91.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/ata/pata_at91.c b/drivers/ata/pata_at91.c
index d1aaeb5..3c2bf86 100644
--- a/drivers/ata/pata_at91.c
+++ b/drivers/ata/pata_at91.c
@@ -33,11 +33,12 @@


#define DRV_NAME "pata_at91"
-#define DRV_VERSION "0.1"
+#define DRV_VERSION "0.2"

#define CF_IDE_OFFSET 0x00c00000
#define CF_ALT_IDE_OFFSET 0x00e00000
#define CF_IDE_RES_SIZE 0x08
+#define NCS_RD_PULSE_LIMIT 0x3f /* maximal value for pulse bitfields */

struct at91_ide_info {
unsigned long mode;
@@ -110,6 +111,11 @@ static void set_smc_timing(struct device *dev,
/* (CS0, CS1, DIR, OE) <= (CFCE1, CFCE2, CFRNW, NCSX) timings */
ncs_read_setup = 1;
ncs_read_pulse = read_cycle - 2;
+ if (ncs_read_pulse > NCS_RD_PULSE_LIMIT) {
+ ncs_read_pulse = NCS_RD_PULSE_LIMIT;
+ dev_warn(dev, "ncs_read_pulse limited to maximal value %lu\n",
+ ncs_read_pulse);
+ }

/* Write timings same as read timings */
write_cycle = read_cycle;
--
1.7.1

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