[PATCH 6/9] ddr: fsl: Fix fsl_ddr_sdram_size() for 4GB modules with 32-bit phys_size_t

Pali Rohár
2022-09-09T15:33:39Z

Function fsl_ddr_compute() always return size in unsigned long long type,
but function fsl_ddr_sdram_size() returns size in phys_size_t type.

When 36-bit addressing mode is not enabled then phys_size_t type is only
32-bit and thus it cannot store value 4GB (0x100000000). Function
fsl_ddr_sdram_size() in this case returns truncated value 0x0.

Fix this issue by returning the highest representable value, which is
0xffffffff (4GB - 1 byte).

This change fixes crashing of proper U-Boot because it detected 4 GB module
as RAM with zero size.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
drivers/ddr/fsl/main.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/ddr/fsl/main.c b/drivers/ddr/fsl/main.c
index ec040f265da2..dd55e61a7a73 100644
--- a/drivers/ddr/fsl/main.c
+++ b/drivers/ddr/fsl/main.c
@@ -949,5 +949,9 @@ fsl_ddr_sdram_size(void)
/* Compute it once normally. */
total_memory = fsl_ddr_compute(&info, STEP_GET_SPD, 1);

+ /* Ensure that total_memory does not overflow on return */
+ if (total_memory > (phys_size_t)~0ULL)
+ total_memory = (phys_size_t)~0ULL;
+
return total_memory;
}
--
2.20.1