On 11/21/25 3:26 PM, Simon Glass wrote:
Hi Marek,
On Thu, 20 Nov 2025 at 21:39, Marek Vasut <[email protected]> wrote:
On 11/21/25 12:40 AM, Simon Glass wrote:
Hi Marek,
On Thu, 20 Nov 2025 at 04:56, Marek Vasut <[email protected]> wrote:
On 11/20/25 10:08 AM, Heiko Schocher wrote:
Hello Heiko,
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
index 380a9f8f3ad..d0e9dad7202 100644
--- a/drivers/i2c/i2c-uclass.c
+++ b/drivers/i2c/i2c-uclass.c
@@ -749,8 +749,11 @@ static int i2c_post_probe(struct udevice *dev)
#if CONFIG_IS_ENABLED(OF_REAL)
struct dm_i2c_bus *i2c = dev_get_uclass_priv(dev);
- i2c->speed_hz = dev_read_u32_default(dev, "clock-frequency",
- I2C_SPEED_STANDARD_RATE);
+ if (!dev_has_ofnode(dev))
+ i2c->speed_hz = I2C_SPEED_STANDARD_RATE;
+ else
+ i2c->speed_hz = dev_read_u32_default(dev, "clock-frequency",
+ I2C_SPEED_STANDARD_RATE);
return dm_i2c_set_bus_speed(dev, i2c->speed_hz);
#else
This sounds more as a bug of dev_read_u32_default() to me and should
be fixed there, else we need to make this check around each call of
dev_read_u32_default() ...
And looking into u-boot:/drivers/core/read.c there are more
candidates for such a fix (all with "default" in function name?)
and such a fix would also make the dev_has_ofnode(dev) check in
i2c_child_post_bind() obsolete.
Or may we fix the default functions in drivers/core/ofnode.c ?
No, this was the previous implementation which is now superseded by this
one, see [1] [2]. The goal is to fix the entry points which pass invalid
content further into U-Boot DT handling code, so the DT validation
happens only one, on DT input, and not again later.
Do the libfdt functions work correctly with *any* negative numbers?
Not without a full tree check (LIBFDT_ASSUME_MASK=0x00). With
LIBFDT_ASSUME_MASK=0xff (what SPL uses, tree checks disabled), passing
negative offset to libfdt functions would simply trigger a segfault for
sandbox SPL tests.
Do
you have a pointer to the libfdt commit which changed this? All of
driver model relies on that behaviour in libfdt:
With libfdt 1.7.2 , this code triggers segfault in sandbox SPL tests:
162 uint32_t fdt_next_tag(const void *fdt, int startoffset, int *nextoffset)
163 {
164 const fdt32_t *tagp, *lenp;
165 uint32_t tag, len, sum;
166 int offset = startoffset;
167 const char *p;
168
169 *nextoffset = -FDT_ERR_TRUNCATED;
170 tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
171 if (!can_assume(VALID_DTB) && !tagp)
172 return FDT_END; /* premature end */
173 tag = fdt32_to_cpu(*tagp);
The fdt_offset_ptr() returns NULL and fdt32_to_cpu(*tagp) would
dereference that NULL pointer.
Ah, I see. So the library hasn't changed, it's just the 'assume'
logic. That makes sense.
I see a few options:
- enable the checks for the affected board (code-size impact)
Every system that enables OF_PLATDATA is affected ?
- create a new VALID_OFFSET assumption (split out from VALID_DTB)
which checks offsets in fdt_next_tag()
The latter might be best. It would likely be very cheap in terms of
code size. In fact, I should have thought of this at the time.
Wouldn't it be better to not misuse libfdt ?
