[PATCH 3/8] memory: emif: handle overflow for timing for LP mode

From: Lokesh Vutla
Date: Mon Mar 11 2013 - 01:07:48 EST


From: Nishanth Menon <nm@xxxxxx>

In case the custom timings provide values which overflow
the maximum possible field value, warn and use maximum
permissible value.

Signed-off-by: Nishanth Menon <nm@xxxxxx>
Signed-off-by: Lokesh Vutla <lokeshvutla@xxxxxx>
---
drivers/memory/emif.c | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/memory/emif.c b/drivers/memory/emif.c
index 16f5089..37e0c77 100644
--- a/drivers/memory/emif.c
+++ b/drivers/memory/emif.c
@@ -715,6 +715,8 @@ static u32 get_pwr_mgmt_ctrl(u32 freq, struct emif_data *emif, u32 ip_rev)
u32 timeout_perf = EMIF_LP_MODE_TIMEOUT_PERFORMANCE;
u32 timeout_pwr = EMIF_LP_MODE_TIMEOUT_POWER;
u32 freq_threshold = EMIF_LP_MODE_FREQ_THRESHOLD;
+ u32 mask;
+ u8 shift;

struct emif_custom_configs *cust_cfgs = emif->plat_data->custom_configs;

@@ -739,27 +741,45 @@ static u32 get_pwr_mgmt_ctrl(u32 freq, struct emif_data *emif, u32 ip_rev)

switch (lpmode) {
case EMIF_LP_MODE_CLOCK_STOP:
- pwr_mgmt_ctrl = (timeout << CS_TIM_SHIFT) |
- SR_TIM_MASK | PD_TIM_MASK;
+ shift = CS_TIM_SHIFT;
+ mask = CS_TIM_MASK;
break;
case EMIF_LP_MODE_SELF_REFRESH:
/* Workaround for errata i735 */
if (timeout < 6)
timeout = 6;

- pwr_mgmt_ctrl = (timeout << SR_TIM_SHIFT) |
- CS_TIM_MASK | PD_TIM_MASK;
+ shift = SR_TIM_SHIFT;
+ mask = SR_TIM_MASK;
break;
case EMIF_LP_MODE_PWR_DN:
- pwr_mgmt_ctrl = (timeout << PD_TIM_SHIFT) |
- CS_TIM_MASK | SR_TIM_MASK;
+ shift = PD_TIM_SHIFT;
+ mask = PD_TIM_MASK;
break;
case EMIF_LP_MODE_DISABLE:
default:
- pwr_mgmt_ctrl = CS_TIM_MASK |
- PD_TIM_MASK | SR_TIM_MASK;
+ mask = 0;
+ shift = 0;
+ break;
+ }
+ /* Round to maximum in case of overflow, BUT warn! */
+ if (lpmode != EMIF_LP_MODE_DISABLE && timeout > mask >> shift) {
+ pr_err("TIMEOUT Overflow - lpmode=%d perf=%d pwr=%d freq=%d\n",
+ lpmode,
+ timeout_perf,
+ timeout_pwr,
+ freq_threshold);
+ WARN(1, "timeout=0x%02x greater than 0x%02x. Using max\n",
+ timeout, mask >> shift);
+ timeout = mask >> shift;
}

+ /* Setup required timing */
+ pwr_mgmt_ctrl = (timeout << shift) & mask;
+ /* setup a default mask for rest of the modes */
+ pwr_mgmt_ctrl |= (SR_TIM_MASK | CS_TIM_MASK | PD_TIM_MASK) &
+ ~mask;
+
/* No CS_TIM in EMIF_4D5 */
if (ip_rev == EMIF_4D5)
pwr_mgmt_ctrl &= ~CS_TIM_MASK;
--
1.7.9.5

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