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drm/ast: Use constants for SDRAM registers

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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.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patch.msgid.link/20260327133532.79696-9-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2026-03-27 14:33:00 +01:00
parent a0320ef5a9
commit 5da1fcb9cb
2 changed files with 17 additions and 7 deletions
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17
drivers/gpu/drm/ast/ast_2500.c
View File

@ -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 {

7
drivers/gpu/drm/ast/ast_reg.h
View File

@ -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