On some platforms (e.g. MPC5200) a direct 1:1 mapping may cause problems with JFFS2 usage, as the local bus (LPB) doesn't support unaligned accesses as implemented in the JFFS2 code via memcpy(). By defining "no-unaligned-direct-access", the flash will not be exposed directly to the MTD users (e.g. JFFS2) any more.
Signed-off-by: Stefan Roese <[email protected]> Cc: Stephan Gatzka <[email protected]> Cc: Anatolij Gustschin <[email protected]> Cc: Albrecht Dress <[email protected]> Cc: Artem Bityutskiy <[email protected]> Cc: David Woodhouse <[email protected]> --- v2: - Changed "map-indirect" to "no-unaligned-direct-access" because of David's comments. Documentation/devicetree/bindings/mtd/mtd-physmap.txt | 7 +++++++ drivers/mtd/maps/physmap_of.c | 14 ++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/Documentation/devicetree/bindings/mtd/mtd-physmap.txt b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt index a63c2bd7..94de19b 100644 --- a/Documentation/devicetree/bindings/mtd/mtd-physmap.txt +++ b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt @@ -16,6 +16,13 @@ file systems on embedded devices. - #address-cells, #size-cells : Must be present if the device has sub-nodes representing partitions (see below). In this case both #address-cells and #size-cells must be equal to 1. + - no-unaligned-direct-access: boolean to disable the default direct + mapping of the flash. + On some platforms (e.g. MPC5200) a direct 1:1 mapping may cause + problems with JFFS2 usage, as the local bus (LPB) doesn't support + unaligned accesses as implemented in the JFFS2 code via memcpy(). + By defining "no-unaligned-direct-access", the flash will not be + exposed directly to the MTD users (e.g. JFFS2) any more. For JEDEC compatible devices, the following additional properties are defined: diff --git a/drivers/mtd/maps/physmap_of.c b/drivers/mtd/maps/physmap_of.c index 2e6fb68..6f19aca 100644 --- a/drivers/mtd/maps/physmap_of.c +++ b/drivers/mtd/maps/physmap_of.c @@ -169,6 +169,7 @@ static int __devinit of_flash_probe(struct platform_device *dev) struct mtd_info **mtd_list = NULL; resource_size_t res_size; struct mtd_part_parser_data ppdata; + bool map_indirect; match = of_match_device(of_flash_match, &dev->dev); if (!match) @@ -192,6 +193,8 @@ static int __devinit of_flash_probe(struct platform_device *dev) } count /= reg_tuple_size; + map_indirect = of_property_read_bool(dp, "no-unaligned-direct-access"); + err = -ENOMEM; info = kzalloc(sizeof(struct of_flash) + sizeof(struct of_flash_list) * count, GFP_KERNEL); @@ -247,6 +250,17 @@ static int __devinit of_flash_probe(struct platform_device *dev) simple_map_init(&info->list[i].map); + /* + * On some platforms (e.g. MPC5200) a direct 1:1 mapping + * may cause problems with JFFS2 usage, as the local bus (LPB) + * doesn't support unaligned accesses as implemented in the + * JFFS2 code via memcpy(). By setting NO_XIP, the + * flash will not be exposed directly to the MTD users + * (e.g. JFFS2) any more. + */ + if (map_indirect) + info->list[i].map.phys = NO_XIP; + if (probe_type) { info->list[i].mtd = do_map_probe(probe_type, &info->list[i].map); -- 1.7.11.2 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
