On 7/31/2024 2:56 PM, Vinod Koul wrote:
On 29-07-24, 16:25, Pierre-Louis Bossart wrote:
On 7/29/24 16:01, Krzysztof Kozlowski wrote:
Two bitmasks in 'struct sdw_slave_prop' - 'source_ports' and
'sink_ports' - define which ports to program in
sdw_program_slave_port_params(). The masks are used to get the
appropriate data port properties ('struct sdw_get_slave_dpn_prop') from
an array.
Bitmasks can be non-continuous or can start from index different than 0,
thus when looking for matching port property for given port, we must
iterate over mask bits, not from 0 up to number of ports.
This fixes allocation and programming slave ports, when a source or sink
masks start from further index.
Fixes: f8101c74aa54 ("soundwire: Add Master and Slave port programming")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
This is a valid change to optimize how the port are accessed.
But the commit message is not completely clear, the allocation in
mipi_disco.c is not modified and I don't think there's anything that
would crash. If there are non-contiguous ports, we will still allocate
space that will not be initialized/used.
/* Allocate memory for set bits in port lists */
nval = hweight32(prop->source_ports);
prop->src_dpn_prop = devm_kcalloc(&slave->dev, nval,
sizeof(*prop->src_dpn_prop),
GFP_KERNEL);
if (!prop->src_dpn_prop)
return -ENOMEM;
/* Read dpn properties for source port(s) */
sdw_slave_read_dpn(slave, prop->src_dpn_prop, nval,
prop->source_ports, "source");
IOW, this is a valid change, but it's an optimization, not a fix in the
usual sense of 'kernel oops otherwise'.
Am I missing something?
BTW, the notion of DPn is that n > 0. DP0 is a special case with
different properties, BIT(0) cannot be set for either of the sink/source
port bitmask.
The fix seems right to me, we cannot have assumption that ports are
contagious, so we need to iterate over all valid ports and not to N
ports which code does now!
Sorry to jump in after the commit was applied. But, it breaks my test.
The point is that dpn_prop[i].num where the i is the array index, and
num is the port number. So, `for (i = 0; i < num_ports; i++)` will iterate
over all valid ports.
We can see in below drivers/soundwire/mipi_disco.c
nval = hweight32(prop->sink_ports);
prop->sink_dpn_prop = devm_kcalloc(&slave->dev, nval,
sizeof(*prop->sink_dpn_prop),
GFP_KERNEL);
And sdw_slave_read_dpn() set data port properties one by one.
`for_each_set_bit(i, &mask, 32)` will break the system when port numbers
are not continuous. For example, a codec has source port number = 1 and 3,
then dpn_prop[0].num = 1 and dpn_prop[1].num = 3. And we need to go
throuth dpn_prop[0] and dpn_prop[1] instead of dpn_prop[1] and dpn_prop[3].
---
drivers/soundwire/stream.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
index 7aa4900dcf31..f275143d7b18 100644
--- a/drivers/soundwire/stream.c
+++ b/drivers/soundwire/stream.c
@@ -1291,18 +1291,18 @@ struct sdw_dpn_prop *sdw_get_slave_dpn_prop(struct sdw_slave *slave,
unsigned int port_num)
{
struct sdw_dpn_prop *dpn_prop;
- u8 num_ports;
+ unsigned long mask;
int i;
if (direction == SDW_DATA_DIR_TX) {
- num_ports = hweight32(slave->prop.source_ports);
+ mask = slave->prop.source_ports;
dpn_prop = slave->prop.src_dpn_prop;
} else {
- num_ports = hweight32(slave->prop.sink_ports);
+ mask = slave->prop.sink_ports;
dpn_prop = slave->prop.sink_dpn_prop;
}
- for (i = 0; i < num_ports; i++) {
+ for_each_set_bit(i, &mask, 32) {
if (dpn_prop[i].num == port_num)
return &dpn_prop[i];
}
