On 30/07/2024 10:23, Krzysztof Kozlowski wrote: > On 29/07/2024 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. > > I think we speak about two different things. port num > 1, that's > correct. But index for src_dpn_prop array is something different. Look > at mipi-disco sdw_slave_read_dpn(): > > 173 u32 bit, i = 0; > ... > 178 addr = ports; > 179 /* valid ports are 1 to 14 so apply mask */ > 180 addr &= GENMASK(14, 1); > 181 > 182 for_each_set_bit(bit, &addr, 32) { > ... > 186 dpn[i].num = bit; > > > so dpn[0..i] = 1..n > where i is also the bit in the mask. > > Similar implementation was done in Qualcomm wsa and wcd codecs like: > array indexed from 0: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/soc/codecs/wcd938x-sdw.c?h=v6.11-rc1#n51 > > genmask from 0, with a mistake: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/soc/codecs/wcd938x-sdw.c?h=v6.11-rc1#n1255 > > The mistake I corrected here: > https://lore.kernel.org/all/20240726-asoc-wcd-wsa-swr-ports-genmask-v1-0-d4d7a8b56f05@xxxxxxxxxx/ > > To summarize, the mask does not denote port numbers (1...14) but indices > of the dpn array which are from 0..whatever (usually -1 from port number). > Let me also complete this with a real life example of my work in progress. I want to use same dpn_prop array for sink and source ports and use different masks. The code in progress is: https://git.codelinaro.org/krzysztof.kozlowski/linux/-/commit/ef709a0e8ab2498751305367e945df18d7a05c78#6f965d7b74e712a5cfcbc1cca407b85443a66bac_2147_2157 Without this patch, I get -EINVAL from sdw_get_slave_dpn_prop(): soundwire sdw-master-1-0: Program transport params failed: -22 Best regards, Krzysztof