target/linux/ramips/patches-5.10/325-mt7621-fix-memory-detect.patch

   1 --- a/arch/mips/ralink/mt7621.c
   2 +++ b/arch/mips/ralink/mt7621.c
   3 @@ -56,7 +56,9 @@
   4  #define MT7621_GPIO_MODE_SDHCI_SHIFT   18
   5  #define MT7621_GPIO_MODE_SDHCI_GPIO    1
   6
   7 -static void *detect_magic __initdata = detect_memory_region;
   8 +#define MT7621_MEM_TEST_PATTERN         0xaa5555aa
   9 +
  10 +static u32 detect_magic __initdata;
  11
  12  static struct rt2880_pmx_func uart1_grp[] =  { FUNC("uart1", 0, 1, 2) };
  13  static struct rt2880_pmx_func i2c_grp[] =  { FUNC("i2c", 0, 3, 2) };
  14 @@ -142,24 +144,32 @@ static struct clk *__init mt7621_add_sys
  15         return clk;
  16  }
  17
  18 +static bool __init mt7621_addr_wraparound_test(phys_addr_t size)
  19 +{
  20 +       void *dm = (void *)KSEG1ADDR(&detect_magic);
  21 +       if (CPHYSADDR(dm + size) >= MT7621_LOWMEM_MAX_SIZE)
  22 +               return true;
  23 +       __raw_writel(MT7621_MEM_TEST_PATTERN, dm);
  24 +       if (__raw_readl(dm) != __raw_readl(dm + size))
  25 +               return false;
  26 +       __raw_writel(!MT7621_MEM_TEST_PATTERN, dm);
  27 +       return __raw_readl(dm) == __raw_readl(dm + size);
  28 +}
  29 +
  30  void __init mt7621_memory_detect(void)
  31  {
  32 -       void *dm = &detect_magic;
  33         phys_addr_t size;
  34
  35 -       for (size = 32 * SZ_1M; size < 256 * SZ_1M; size <<= 1) {
  36 -               if (!__builtin_memcmp(dm, dm + size, sizeof(detect_magic)))
  37 -                       break;
  38 +       for (size = 32 * SZ_1M; size <= 256 * SZ_1M; size <<= 1) {
  39 +               if (mt7621_addr_wraparound_test(size)) {
  40 +                       memblock_add(MT7621_LOWMEM_BASE, size);
  41 +                       return;
  42 +               }
  43         }
  44
  45 -       if ((size == 256 * SZ_1M) &&
  46 -           (CPHYSADDR(dm + size) < MT7621_LOWMEM_MAX_SIZE) &&
  47 -           __builtin_memcmp(dm, dm + size, sizeof(detect_magic))) {
  48 -               memblock_add(MT7621_LOWMEM_BASE, MT7621_LOWMEM_MAX_SIZE);
  49 -               memblock_add(MT7621_HIGHMEM_BASE, MT7621_HIGHMEM_SIZE);
  50 -       } else {
  51 -               memblock_add(MT7621_LOWMEM_BASE, size);
  52 -       }
  53 +       /* addr doesn't wrap around at dm + 256M, assume 512M memory. */
  54 +       memblock_add(MT7621_LOWMEM_BASE, MT7621_LOWMEM_MAX_SIZE);
  55 +       memblock_add(MT7621_HIGHMEM_BASE, MT7621_HIGHMEM_SIZE);
  56  }
  57
  58  void __init ralink_clk_init(void)