Hello Sudeep,
On 2/2/23 15:30, Sudeep Holla wrote:
As per the SCMI specification, section CLOCK_DESCRIBE_RATES mentions that
the value of num_rates_flags[11:0] in the response must be 3 if the return
format is the triplet. Due to the buggy firmware, this was not noticed for
long time. The firmware is now fixed resulting in ClockDescribeRates() to
fail with "Buffer Too Small" error as the RequiredArraySize gets miscalculated
as 72 instead of 24.
Fix the issue by reusing the logic for both the return format which must
work if num_rates_flags has correct value as expected from the specification.
Cc: Pierre Gondois <pierre.gond...@arm.com>
Cc: Girish Pathak <girish.pat...@arm.com>
Cc: Jeff Brasen <jbra...@nvidia.com>
Reported-by: Sami Mujawar <sami.muja...@arm.com>
Signed-off-by: Sudeep Holla <sudeep.ho...@arm.com>
---
ArmPkg/Drivers/ArmScmiDxe/ScmiClockProtocol.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
Hi All,
Sorry for the resend, I hadn't subscribed before so resending after the
subscription.
Regards,
Sudeep
diff --git a/ArmPkg/Drivers/ArmScmiDxe/ScmiClockProtocol.c
b/ArmPkg/Drivers/ArmScmiDxe/ScmiClockProtocol.c
index 12a7e6df5d43..1412717bc227 100644
--- a/ArmPkg/Drivers/ArmScmiDxe/ScmiClockProtocol.c
+++ b/ArmPkg/Drivers/ArmScmiDxe/ScmiClockProtocol.c
@@ -236,12 +236,7 @@ ClockDescribeRates (
*TotalRates = NUM_RATES (DescribeRates->NumRatesFlags)
+ NUM_REMAIN_RATES (DescribeRates->NumRatesFlags);
- if (*Format == ScmiClockRateFormatDiscrete) {
- RequiredArraySize = (*TotalRates) * sizeof (UINT64);
- } else {
- // We need to return triplet of 64 bit value for each rate
- RequiredArraySize = (*TotalRates) * 3 * sizeof (UINT64);
- }
+ RequiredArraySize = (*TotalRates) * sizeof (UINT64);
if (RequiredArraySize > (*RateArraySize)) {
*RateArraySize = RequiredArraySize;
I think the following also needs to be modified:
"""
for (RateNo = 0; RateNo < NUM_RATES (DescribeRates->NumRatesFlags); RateNo++) {
// Linear clock rates from minimum to maximum in steps
// Minimum clock rate.
Rate = &DescribeRates->Rates[RateOffset++];
RateArray[RateIndex].ContinuousRate.Min =
ConvertTo64Bit (Rate->Low, Rate->High);
Rate = &DescribeRates->Rates[RateOffset++];
// Maximum clock rate.
RateArray[RateIndex].ContinuousRate.Max =
ConvertTo64Bit (Rate->Low, Rate->High);
Rate = &DescribeRates->Rates[RateOffset++];
// Step.
RateArray[RateIndex++].ContinuousRate.Step =
ConvertTo64Bit (Rate->Low, Rate->High);
}
"""
If the clock format is continuous, then per spec:
NUM_RATES (DescribeRates->NumRatesFlags) == 3
However 3 rates are read per loop here. So I think the
loop needs to be removed aswell.
Without this additional change, I get:
"""
Synchronous Exception at 0xA2D0E6EBD20F8604
Synchronous Exception at 0xA2D0E6EBD20F8604
PC 0xA2D0E6EBD20F8604
Recursive exception occurred while dumping the CPU state
"""
With the above loop removed:
Reviewed-by: Pierre Gondois <pierre.gond...@arm.com>
Tested-by: Pierre Gondois <pierre.gond...@arm.com>
Regards,
Pierre
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