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@vger.kernel.org Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org
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!
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;
num_ports = hweight32(slave->prop.sink_ports);
mask = slave->prop.sink_ports;
- 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]; }