Le 16/09/2019 à 08:28, Dan Carpenter a écrit :
On Fri, Sep 13, 2019 at 09:57:09AM +0200, Maxime Ripard wrote:
Hi Christophe,
On Thu, Sep 12, 2019 at 10:44:50PM +0200, Christophe JAILLET wrote:
The 2nd parameter of 'find_first_zero_bit()' is a number of bits, not of
bytes. So use 'BITS_PER_LONG' instead of 'sizeof(lanes_used)'.
Fixes: 1fc3b37f34f6 ("media: v4l: cadence: Add Cadence MIPI-CSI2 RX driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
This patch is purely speculative. Using BITS_PER_LONG looks logical to me,
but I'm not 100% sure that it is what is expected here. 'csi2rx->max_lanes'
could also be a good candidate.
Yeah, csi2rx->max_lanes would make more sense in that context. Could
you resend a new version?
This is sort of unrelated, but for Smatch purposes the csi2rx->max_lanes
comes from the firmware in csi2rx_parse_dt() and it could be any u8
value.
Hi Dan,
not sure to follow you.
csi2rx_probe()
--> csi2rx_get_resources()
--> ...
dev_cfg = readl(csi2rx->base + CSI2RX_DEVICE_CFG_REG);
...
csi2rx->max_lanes = dev_cfg & 7;
if (csi2rx->max_lanes > CSI2RX_LANES_MAX) {
dev_err(&pdev->dev, "Invalid number of lanes: %u\n",
csi2rx->max_lanes);
return -EINVAL;
}
So I guess, that we can trust max_lanes because of the 'if (... >
CSI2RX_LANES_MAX)' check.
Did I miss something?
I sort of wish that people would write code which was known to be
correct just from reading the kernel code, without looking at the
firmware... I guess I could mark v4l2_fwnode_endpoint_parse() as always
giving us valid data, but that still wouldn't tell us what the valid
data is. It's hard to know the right answer from a static analysis
point of view.
regards,
dan carpenter
