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imx233: handle quirk about OF partition address bug/feature

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Change-Id: Ib8b854ce7132ac460672f9adf8611f580ca53746
This commit is contained in:
Amaury Pouly 2014-01-05 15:21:04 +01:00
parent 69d0dae55b
commit 877eb7a112
1 changed files with 17 additions and 9 deletions
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26
firmware/target/arm/imx233/partitions-imx233.c
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@ -125,14 +125,22 @@ static int compute_window_freescale(intptr_t user, part_read_fn_t read_fn,
* The first table uses 512-byte sector size and the second one usually uses
* 2048-byte logical sector size.
*
* We restrict the window to the user partition
*
* WARNING HACK FIXME BUG
* Reverse engineering and experiments suggests that the OF ignores the lowest 2 bits
* of the LBAs in the partition table. There is at least one example
* (the Creative Zen X-Fi3) where this is important because the LBA of the user partition
* is not a multiple of 4. The behaviour of the size field is less clear but
* it seems that it is similarly truncated. */
* Reverse engineering suggests that OF has a notion of "internal sector size"
* which can either be 512 or 2048 bytes. When applied to the main data drive,
* it internally converts LBA from sectors to "internal sectors". Consequently,
* if the internal sector size is 2048 and the sector size of 512, it will
* drop the lowest 2 bits of the LBA from the partition table. This is the case
* of the ZEN X-Fi3 for example. However, if the internal sector size is 512
* bytes, then there is no such loss. This is the case of the Zen X-Fi Style
* for example.
* The behaviour of the size field is less clear but it seems that it is similarly
* truncated. */
#if defined(CREATIVE_ZENXFISTYLE)
#define DROP_MASK 0
#else
#define DROP_MASK 3
#endif
if(mbr[510] != 0x55 || mbr[511] != 0xAA)
return -101; /* invalid MBR */
if(part == IMX233_PART_DATA)
@ -141,9 +149,9 @@ static int compute_window_freescale(intptr_t user, part_read_fn_t read_fn,
uint8_t *ent = &mbr[446];
*start = ent[8] | ent[9] << 8 | ent[10] << 16 | ent[11] << 24;
/* ignore two lowest bits(see comment above) */
*start &= ~3;
*start &= ~DROP_MASK;
*end = (ent[12] | ent[13] << 8 | ent[14] << 16 | ent[15] << 24);
*end &= ~3;
*end &= ~DROP_MASK;
/* ignore two lowest bits(order is important, first truncate then add start) */
*end += *start;