On 23/03/2026 16:56, Thomas Zimmermann wrote:
Aspeed hardware allows for acceessing the SDRAM from the host. SDRAM
registers are located at the memory range at [0x80000000, 0xffffffff].
Refer to memory access with the macro AST_SDRAM(). Also add a TODO item
for the nonsensical documentation next to its caller.
Thanks, it looks good to me.
Reviewed-by: Jocelyn Falempe <[email protected]>
Signed-off-by: Thomas Zimmermann <[email protected]>
---
drivers/gpu/drm/ast/ast_2500.c | 17 ++++++++++-------
drivers/gpu/drm/ast/ast_reg.h | 7 +++++++
2 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/ast/ast_2500.c b/drivers/gpu/drm/ast/ast_2500.c
index f0639f1ef062..39f401dd1f47 100644
--- a/drivers/gpu/drm/ast/ast_2500.c
+++ b/drivers/gpu/drm/ast/ast_2500.c
@@ -225,6 +225,9 @@ static void ddr_phy_init_2500(struct ast_device *ast)
}
/*
+ * TODO: Review and fix the comments. The function below only detects
+ * up to 1 GiB of SDRAM.
+ *
* Check DRAM Size
* 1Gb : 0x80000000 ~ 0x87FFFFFF
* 2Gb : 0x80000000 ~ 0x8FFFFFFF
@@ -238,21 +241,21 @@ static void check_dram_size_2500(struct ast_device *ast,
u32 tRFC)
reg_04 = ast_mindwm(ast, AST_REG_MCR04) & 0xfffffffc;
reg_14 = ast_mindwm(ast, AST_REG_MCR14) & 0xffffff00;
- ast_moutdwm(ast, 0xA0100000, 0x41424344);
- ast_moutdwm(ast, 0x90100000, 0x35363738);
- ast_moutdwm(ast, 0x88100000, 0x292A2B2C);
- ast_moutdwm(ast, 0x80100000, 0x1D1E1F10);
+ ast_moutdwm(ast, AST_SDRAM(0x20100000), 0x41424344);
+ ast_moutdwm(ast, AST_SDRAM(0x10100000), 0x35363738);
+ ast_moutdwm(ast, AST_SDRAM(0x08100000), 0x292A2B2C);
+ ast_moutdwm(ast, AST_SDRAM(0x00100000), 0x1D1E1F10);
/* Check 8Gbit */
- if (ast_mindwm(ast, 0xA0100000) == 0x41424344) {
+ if (ast_mindwm(ast, AST_SDRAM(0x20100000)) == 0x41424344) {
reg_04 |= 0x03;
reg_14 |= (tRFC >> 24) & 0xFF;
/* Check 4Gbit */
- } else if (ast_mindwm(ast, 0x90100000) == 0x35363738) {
+ } else if (ast_mindwm(ast, AST_SDRAM(0x10100000)) == 0x35363738) {
reg_04 |= 0x02;
reg_14 |= (tRFC >> 16) & 0xFF;
/* Check 2Gbit */
- } else if (ast_mindwm(ast, 0x88100000) == 0x292A2B2C) {
+ } else if (ast_mindwm(ast, AST_SDRAM(0x08100000)) == 0x292A2B2C) {
reg_04 |= 0x01;
reg_14 |= (tRFC >> 8) & 0xFF;
} else {
diff --git a/drivers/gpu/drm/ast/ast_reg.h b/drivers/gpu/drm/ast/ast_reg.h
index 5effe6897b51..78fabe2a9c81 100644
--- a/drivers/gpu/drm/ast/ast_reg.h
+++ b/drivers/gpu/drm/ast/ast_reg.h
@@ -209,4 +209,11 @@
#define AST_REG_WDT1C(__n) AST_REG_WDT((__n), 0x1c)
#define AST_REG_WDT2C(__n) AST_REG_WDT((__n), 0x2c)
+/*
+ * SDRAM (0x80000000 - 0xffffffff)
+ */
+
+#define AST_SDRAM_BASE (0x80000000)
+#define AST_SDRAM(__offset) (AST_SDRAM_BASE + (__offset))
+
#endif
