[PATCH 7/9] ddr: fsl: Allow to detect 4 GB DDR modules in 32-bit mode

Pali Rohár
2022-09-09T15:34:34Z

U-Boot core code already handles the case when RAM size is bigger than
CONFIG_MAX_MEM_MAPPED. So there is no need to do duplicate check in fsl ddr
driver for CONFIG_MAX_MEM_MAPPED. Instead simplify code to just check if
RAM size can be representable in phys_size_t type. And avoid printing
warning if phys_size_t is just 1 byte smaller than RAM size, which is the
typical situation with 4 GB DDR module.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
drivers/ddr/fsl/main.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/ddr/fsl/main.c b/drivers/ddr/fsl/main.c
index dd55e61a7a73..577ca569b042 100644
--- a/drivers/ddr/fsl/main.c
+++ b/drivers/ddr/fsl/main.c
@@ -856,15 +856,18 @@ phys_size_t __fsl_ddr_sdram(fsl_ddr_info_t *pinfo)
debug("total_memory by %s = %llu\n", __func__, total_memory);

#if !defined(CONFIG_PHYS_64BIT)
- /* Check for more than max memory. Bad. */
- if ((first_ctrl == 0) && (total_memory > CONFIG_MAX_MEM_MAPPED)) {
+ /*
+ * Show warning about big DDR moodules. But avoid warning for 4 GB DDR
+ * modules when U-Boot supports RAM of maximal size 4 GB - 1 byte.
+ */
+ if ((first_ctrl == 0) && (total_memory - 1 > (phys_size_t)~0ULL)) {
puts("Detected ");
print_size(total_memory, " of memory\n");
#ifndef CONFIG_SPL_BUILD
puts(" "); /* re-align to match init_dram print */
#endif
puts("This U-Boot only supports <= ");
- print_size(CONFIG_MAX_MEM_MAPPED, " of DDR\n");
+ print_size((unsigned long long)((phys_size_t)~0ULL)+1, " of DDR\n");
#ifndef CONFIG_SPL_BUILD
puts(" "); /* re-align to match init_dram print */
#endif
@@ -872,10 +875,13 @@ phys_size_t __fsl_ddr_sdram(fsl_ddr_info_t *pinfo)
#ifndef CONFIG_SPL_BUILD
puts(" "); /* re-align to match init_dram print */
#endif
- total_memory = CONFIG_MAX_MEM_MAPPED;
}
#endif

+ /* 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