Hi,
On 23 July 2015 at 10:51, Stephen Warren swarren@wwwdotorg.org wrote:
From: Thierry Reding treding@nvidia.com
Signed-off-by: Thierry Reding treding@nvidia.com Signed-off-by: Tom Warren twarren@nvidia.com Signed-off-by: Stephen Warren swarren@nvidia.com
Simon,
When Thierry first posted this patch, you responded:
parent = fdt_parent_offset(blob, node);This function is very slow as it must scan the whole tree. Can we instead pass in the parent node?
I don't think that's possible in general. This function is called from fdtdec_get_addr(), and it's easy to find call sites of that function that don't have the parent node available. IIRC, the first couple of example I found scan the DT for a node with a certain compatible value, or look up nodes via aliases, rather than being called while parsing the DT in a top-down tree-like fashion, where the parent node is easily available. I didn't do an exhaustive search after I found a few problematic cases.
Also, how about (in addition) a version of this function that works for devices? Like:
device_get_addr_size(struct udevice *dev, ...)
so that it can handle this for you.
That sounds like a separate patch?
Yes, but I think we should get it in there so that people don't start using this (wildly inefficient) function when they don't need to. I think by passing in the parent node we force people to think about the cost.
Yes the driver model function can be a separate patch, but let's get it in at about the same time. We have dev_get_addr() so could have dev_get_addr_size().
Equally, I see that struct udevice contains an of_offset field, but no parent_of_offset or similar. There is a struct udevice *parent though; is the struct udevice hierarchy guaranteed to 100% match the DT hierarchy? I know this isn't necessarily guaranteed in Linux's device model for example.
Yes it is 100% guaranteed, so dev->parent->of_offset will do the right thing.
As such, this patch seems OK to me as-is.
lib/fdtdec.c | 56 ++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 36 insertions(+), 20 deletions(-)
diff --git a/lib/fdtdec.c b/lib/fdtdec.c index 9c6b3619da24..56e72eafaade 100644 --- a/lib/fdtdec.c +++ b/lib/fdtdec.c @@ -88,29 +88,45 @@ const char *fdtdec_get_compatible(enum fdt_compat_id id) fdt_addr_t fdtdec_get_addr_size(const void *blob, int node, const char *prop_name, fdt_size_t *sizep) {
const fdt_addr_t *cell;int len;
const fdt32_t *ptr, *end;int parent, na, ns, len;fdt_addr_t addr; debug("%s: %s: ", __func__, prop_name);
cell = fdt_getprop(blob, node, prop_name, &len);if (cell && ((!sizep && len == sizeof(fdt_addr_t)) ||len == sizeof(fdt_addr_t) * 2)) {fdt_addr_t addr = fdt_addr_to_cpu(*cell);if (sizep) {const fdt_size_t *size;size = (fdt_size_t *)((char *)cell +sizeof(fdt_addr_t));*sizep = fdt_size_to_cpu(*size);debug("addr=%08lx, size=%llx\n",(ulong)addr, (u64)*sizep);} else {debug("%08lx\n", (ulong)addr);}return addr;
parent = fdt_parent_offset(blob, node);if (parent < 0) {debug("(no parent found)\n");return FDT_ADDR_T_NONE; }
debug("(not found)\n");return FDT_ADDR_T_NONE;
na = fdt_address_cells(blob, parent);ns = fdt_size_cells(blob, parent);ptr = fdt_getprop(blob, node, prop_name, &len);if (!ptr) {debug("(not found)\n");return FDT_ADDR_T_NONE;}end = ptr + len / sizeof(*ptr);if (ptr + na + ns > end) {debug("(not enough data: expected %d bytes, got %d bytes)\n",(na + ns) * 4, len);return FDT_ADDR_T_NONE;}addr = fdtdec_get_number(ptr, na);if (sizep) {*sizep = fdtdec_get_number(ptr + na, ns);debug("addr=%pa, size=%pa\n", &addr, sizep);} else {debug("%pa\n", &addr);}return addr;}
fdt_addr_t fdtdec_get_addr(const void *blob, int node,
1.9.1
Regards, SImon