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authorAlbert Lee <albertcc@tw.ibm.com>2007-07-03 22:28:36 +0200
committerBartlomiej Zolnierkiewicz <bzolnier@gmail.com>2007-07-03 22:28:36 +0200
commit8006bf56e360a4db71d304df778870a371a9e930 (patch)
tree9471ba5fd85ce42c8ec6253893520371762e513e /drivers/ide
parent52374f890c1d0d64148d55a20d995a0b3e0ae987 (diff)
ide: pdc202xx_new PLL input clock fix
Recently the PLL input clock of Promise 2027x is sometimes detected higher 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 measure 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> Cc: Bahadir Balban <bahadir.balban@gmail.com> Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Diffstat (limited to 'drivers/ide')
-rw-r--r--drivers/ide/pci/pdc202xx_new.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/ide/pci/pdc202xx_new.c b/drivers/ide/pci/pdc202xx_new.c
index cc0bfdcf1f19..0765dce6948e 100644
--- a/drivers/ide/pci/pdc202xx_new.c
+++ b/drivers/ide/pci/pdc202xx_new.c
@@ -306,11 +306,13 @@ static long __devinit read_counter(u32 dma_base)
*/
static long __devinit detect_pll_input_clock(unsigned long dma_base)
{
+ struct timeval start_time, end_time;
long start_count, end_count;
- long pll_input;
+ long pll_input, usec_elapsed;
u8 scr1;
start_count = read_counter(dma_base);
+ do_gettimeofday(&start_time);
/* Start the test mode */
outb(0x01, dma_base + 0x01);
@@ -322,6 +324,7 @@ static long __devinit detect_pll_input_clock(unsigned long dma_base)
mdelay(10);
end_count = read_counter(dma_base);
+ do_gettimeofday(&end_time);
/* Stop the test mode */
outb(0x01, dma_base + 0x01);
@@ -333,7 +336,10 @@ static long __devinit detect_pll_input_clock(unsigned long dma_base)
* Calculate the input clock in Hz
* (the clock counter is 30 bit wide and counts down)
*/
- pll_input = ((start_count - end_count) & 0x3ffffff) * 100;
+ usec_elapsed = (end_time.tv_sec - start_time.tv_sec) * 1000000 +
+ (end_time.tv_usec - start_time.tv_usec);
+ pll_input = ((start_count - end_count) & 0x3ffffff) / 10 *
+ (10000000 / usec_elapsed);
DBG("start[%ld] end[%ld]\n", start_count, end_count);