The hardware wait loop in hw_sm750_de_wait used a hardcoded loop
counter (0x10000000), which depends on CPU speed and is unreliable.
Replace the loop counter with a jiffies-based timeout (1 second)
using time_before(). This ensures consistent delays across architectures.
Signed-off-by: Madhumitha Sundar <madhuananda18@gmail.com>
---
Changes in v2:
- Switched from loop counter to jiffies + cpu_relax() as requested by Greg KH.
---
drivers/staging/sm750fb/sm750_hw.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/sm750fb/sm750_hw.c b/drivers/staging/sm750fb/sm750_hw.c
index ce46f240c..b24d27a77 100644
--- a/drivers/staging/sm750fb/sm750_hw.c
+++ b/drivers/staging/sm750fb/sm750_hw.c
@@ -523,19 +523,32 @@ int hw_sm750le_de_wait(void)
int hw_sm750_de_wait(void)
{
- int i = 0x10000000;
+ /* Wait for 1 second (HZ) */
+ unsigned long timeout = jiffies + HZ;
unsigned int mask = SYSTEM_CTRL_DE_STATUS_BUSY |
SYSTEM_CTRL_DE_FIFO_EMPTY |
SYSTEM_CTRL_DE_MEM_FIFO_EMPTY;
+ unsigned int val;
- while (i--) {
- unsigned int val = peek32(SYSTEM_CTRL);
+ /* Run while Current Time is BEFORE the Deadline */
+ while (time_before(jiffies, timeout)) {
+ val = peek32(SYSTEM_CTRL);
+ /* If Not Busy (0) AND Buffers Empty (1), we are good */
if ((val & mask) ==
(SYSTEM_CTRL_DE_FIFO_EMPTY | SYSTEM_CTRL_DE_MEM_FIFO_EMPTY))
return 0;
+
+ /* Polite pause to save power */
+ cpu_relax();
}
- /* timeout error */
+
+ /* Final check in case we succeeded at the last millisecond */
+ val = peek32(SYSTEM_CTRL);
+ if ((val & mask) ==
+ (SYSTEM_CTRL_DE_FIFO_EMPTY | SYSTEM_CTRL_DE_MEM_FIFO_EMPTY))
+ return 0;
+
return -1;
}
--
2.43.0