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Subject[PATCH v2] ide: at91_ide.c bugfix for high master clock
Date
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 IDE device.

Signed-off-by: Igor Plyatov <plyatov@gmail.com>
---
drivers/ide/at91_ide.c | 33 +++++++++++++++++++++++----------
1 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/ide/at91_ide.c b/drivers/ide/at91_ide.c
index 000a78e..5f97710 100644
--- a/drivers/ide/at91_ide.c
+++ b/drivers/ide/at91_ide.c
@@ -36,6 +36,8 @@
#define perr(fmt, args...) pr_err(DRV_NAME ": " fmt, ##args)
#define pdbg(fmt, args...) pr_debug("%s " fmt, __func__, ##args)

+#define NCS_RD_PULSE_LIMIT 0x3f /* maximal value for pulse bitfields */
+
/*
* Access to IDE device is possible through EBI Static Memory Controller
* with Compact Flash logic. For details see EBI and SMC datasheet sections
@@ -70,6 +72,7 @@ static void set_smc_timings(const u8 chipselect, const u16 cycle,
const u16 setup, const u16 pulse,
const u16 data_float, int use_iordy)
{
+ u16 ncs_rd_pulse;
unsigned long mode = AT91_SMC_READMODE | AT91_SMC_WRITEMODE |
AT91_SMC_BAT_SELECT;

@@ -81,19 +84,29 @@ static void set_smc_timings(const u8 chipselect, const u16 cycle,
if (data_float)
mode |= AT91_SMC_TDF_(data_float);

+ ncs_rd_pulse = cycle;
+ if (ncs_rd_pulse > NCS_RD_PULSE_LIMIT) {
+ ncs_rd_pulse = NCS_RD_PULSE_LIMIT;
+ pr_warn(DRV_NAME ": ncs_rd_pulse limited to maximal value %d\n",
+ ncs_rd_pulse);
+ }
+
at91_sys_write(AT91_SMC_MODE(chipselect), mode);

/* setup timings in SMC */
- at91_sys_write(AT91_SMC_SETUP(chipselect), AT91_SMC_NWESETUP_(setup) |
- AT91_SMC_NCS_WRSETUP_(0) |
- AT91_SMC_NRDSETUP_(setup) |
- AT91_SMC_NCS_RDSETUP_(0));
- at91_sys_write(AT91_SMC_PULSE(chipselect), AT91_SMC_NWEPULSE_(pulse) |
- AT91_SMC_NCS_WRPULSE_(cycle) |
- AT91_SMC_NRDPULSE_(pulse) |
- AT91_SMC_NCS_RDPULSE_(cycle));
- at91_sys_write(AT91_SMC_CYCLE(chipselect), AT91_SMC_NWECYCLE_(cycle) |
- AT91_SMC_NRDCYCLE_(cycle));
+ at91_sys_write(AT91_SMC_SETUP(chipselect),
+ AT91_SMC_NWESETUP_(setup) |
+ AT91_SMC_NCS_WRSETUP_(0) |
+ AT91_SMC_NRDSETUP_(setup) |
+ AT91_SMC_NCS_RDSETUP_(0));
+ at91_sys_write(AT91_SMC_PULSE(chipselect),
+ AT91_SMC_NWEPULSE_(pulse) |
+ AT91_SMC_NCS_WRPULSE_(ncs_rd_pulse) |
+ AT91_SMC_NRDPULSE_(pulse) |
+ AT91_SMC_NCS_RDPULSE_(ncs_rd_pulse));
+ at91_sys_write(AT91_SMC_CYCLE(chipselect),
+ AT91_SMC_NWECYCLE_(cycle) |
+ AT91_SMC_NRDCYCLE_(cycle));
}

static unsigned int calc_mck_cycles(unsigned int ns, unsigned int mck_hz)
--
1.7.0.4


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