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authorAlbert Lee <albertcc@tw.ibm.com>2007-06-26 09:43:15 +0400
committerJeff Garzik <jeff@garzik.org>2007-07-02 18:12:34 +0400
commit8c781bf77a339748839bfd5eedfe2ad3e0e05c4a (patch)
treeb36feb822eaecec5735dcc18244503d5bb88e15e /drivers/ata/pata_pdc2027x.c
parentabcdceb9d0bf39da7c7ff8bcdff6eb4d9dfec56f (diff)
downloadlinux-8c781bf77a339748839bfd5eedfe2ad3e0e05c4a.tar.xz
libata: pata_pdc2027x PLL input clock fix
Recently the PLL input clock of pata_pdc2027x is sometimes detected higer than expected (e.g. 20.027 MHz compared to 16.714 MHz). It seems sometimes the mdelay() function is not as precise as it used to be. Per Alan's advice, HT or power management might affect the precision of mdelay(). This patch calls gettimeofday() to mesure the time elapsed and calculate the PLL input clock accordingly. Signed-off-by: Albert Lee <albertcc@tw.ibm.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'drivers/ata/pata_pdc2027x.c')
-rw-r--r--drivers/ata/pata_pdc2027x.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/ata/pata_pdc2027x.c b/drivers/ata/pata_pdc2027x.c
index 0d2cc49fde4b..69a5aa4949f5 100644
--- a/drivers/ata/pata_pdc2027x.c
+++ b/drivers/ata/pata_pdc2027x.c
@@ -689,10 +689,12 @@ static long pdc_detect_pll_input_clock(struct ata_host *host)
void __iomem *mmio_base = host->iomap[PDC_MMIO_BAR];
u32 scr;
long start_count, end_count;
- long pll_clock;
+ struct timeval start_time, end_time;
+ long pll_clock, usec_elapsed;
/* Read current counter value */
start_count = pdc_read_counter(host);
+ do_gettimeofday(&start_time);
/* Start the test mode */
scr = readl(mmio_base + PDC_SYS_CTL);
@@ -705,6 +707,7 @@ static long pdc_detect_pll_input_clock(struct ata_host *host)
/* Read the counter values again */
end_count = pdc_read_counter(host);
+ do_gettimeofday(&end_time);
/* Stop the test mode */
scr = readl(mmio_base + PDC_SYS_CTL);
@@ -713,7 +716,11 @@ static long pdc_detect_pll_input_clock(struct ata_host *host)
readl(mmio_base + PDC_SYS_CTL); /* flush */
/* calculate the input clock in Hz */
- pll_clock = (start_count - end_count) * 10;
+ usec_elapsed = (end_time.tv_sec - start_time.tv_sec) * 1000000 +
+ (end_time.tv_usec - start_time.tv_usec);
+
+ pll_clock = (start_count - end_count) / 100 *
+ (100000000 / usec_elapsed);
PDPRINTK("start[%ld] end[%ld] \n", start_count, end_count);
PDPRINTK("PLL input clock[%ld]Hz\n", pll_clock);