On 12/18/23 06:01, Vinod Koul wrote: > On 07-12-23, 16:29, Pierre-Louis Bossart wrote: >> Add the lookup table required by crc8(). All configuration values were >> directly table from the MIPI SoundWire 1.x specification. >> >> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> >> --- >> drivers/soundwire/Makefile | 4 +- >> drivers/soundwire/crc8.c | 277 +++++++++++++++++++++++++++++++++++++ >> drivers/soundwire/crc8.h | 11 ++ >> 3 files changed, 291 insertions(+), 1 deletion(-) >> create mode 100644 drivers/soundwire/crc8.c >> create mode 100644 drivers/soundwire/crc8.h >> >> diff --git a/drivers/soundwire/Makefile b/drivers/soundwire/Makefile >> index 657f5888a77b..170128dd9318 100644 >> --- a/drivers/soundwire/Makefile >> +++ b/drivers/soundwire/Makefile >> @@ -5,7 +5,9 @@ >> >> #Bus Objs >> soundwire-bus-y := bus_type.o bus.o master.o slave.o mipi_disco.o stream.o \ >> - sysfs_slave.o sysfs_slave_dpn.o >> + sysfs_slave.o sysfs_slave_dpn.o \ >> + crc8.o >> + >> obj-$(CONFIG_SOUNDWIRE) += soundwire-bus.o >> >> soundwire-generic-allocation-objs := generic_bandwidth_allocation.o >> diff --git a/drivers/soundwire/crc8.c b/drivers/soundwire/crc8.c >> new file mode 100644 >> index 000000000000..b6b984d7f39a >> --- /dev/null >> +++ b/drivers/soundwire/crc8.c >> @@ -0,0 +1,277 @@ >> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) >> +// Copyright(c) 2024 Intel Corporation. >> + >> +#include <linux/crc8.h> >> +#include <linux/module.h> >> +#include "crc8.h" >> + >> +/* >> + * the MIPI SoundWire CRC8 polynomial is X^8 + X^6 + X^3 + X^2 + 1, MSB first >> + * The value is (1)01001101 = 0x4D >> + * >> + * the table below was generated with >> + * >> + * u8 crc8_lookup_table[CRC8_TABLE_SIZE]; >> + * crc8_populate_msb(crc8_lookup_table, SDW_CRC8_POLY); > > Good that you found this API, so next question would be why should we > have this static table in kernel and not generate on probe if bpt is > supported..? Many subsystems use these APIs to generate the tables.. The table is going to be the same for all hosts, it's simpler if everyone uses a constant table, no? We're talking about 256 bytes added for the common bus parts, be it with dynamically allocated memory or a static table. I don't mind reverting to a dynamically allocated table populated at boot if that was the consensus.
