diff options
| author | Michael Zaidman <michael.zaidman@gmail.com> | 2022-11-06 00:11:43 +0300 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2022-11-11 13:09:35 +0300 |
| commit | 54410c14800ad652c77e5c6fc5c17baad6e42cb6 (patch) | |
| tree | f86425b222ea6ad646e350eb2a520f8b137f5827 /drivers/hid | |
| parent | 0acb869f40ecc328ed87e389cc08122e3aeba1a8 (diff) | |
| download | linux-54410c14800ad652c77e5c6fc5c17baad6e42cb6.tar.xz | |
HID: ft260: improve i2c large reads performance
The patch increases the read buffer size to 180 bytes. It reduces
the number of ft260_i2c_read() calls by three, improving the big
reads performance.
$ sudo i2ctransfer -y -f 13 w2@0x51 0x0 0x0 r180
Before:
[ +4.071878] ft260_i2c_write_read: off 0x0 rlen 180 wlen 2
[ +0.000005] ft260_i2c_write: rep 0xd0 addr 0x51 off 0 len 2 wlen 2 flag 0x2 d[0] 0x0
[ +0.001097] ft260_xfer_status: bus_status 0x41, clock 100
[ +0.000175] ft260_xfer_status: bus_status 0x40, clock 100
[ +0.000004] ft260_i2c_read: rep 0xc2 addr 0x51 len 180 rlen 60 flag 0x3
[ +0.008579] ft260_raw_event: i2c resp: rep 0xde len 60
[ +0.000208] ft260_xfer_status: bus_status 0x40, clock 100
[ +0.000001] ft260_i2c_read: rep 0xc2 addr 0x51 len 120 rlen 60 flag 0x0
[ +0.008794] ft260_raw_event: i2c resp: rep 0xde len 60
[ +0.000181] ft260_xfer_status: bus_status 0x40, clock 100
[ +0.000002] ft260_i2c_read: rep 0xc2 addr 0x51 len 60 rlen 60 flag 0x4
[ +0.008817] ft260_raw_event: i2c resp: rep 0xde len 60
[ +0.000223] ft260_xfer_status: bus_status 0x20, clock 100
After:
[ +11.611642] ft260_i2c_write_read: off 0x0 rlen 180 wlen 2
[ +0.000005] ft260_i2c_write: rep 0xd0 addr 0x51 off 0 len 2 wlen 2 flag 0x2 d[0] 0x0
[ +0.008001] ft260_xfer_status: bus_status 0x20, clock 100
[ +0.000001] ft260_i2c_read: rep 0xc2 addr 0x51 len 180 rlen 180 flag 0x7
[ +0.008994] ft260_raw_event: i2c resp: rep 0xde len 60
[ +0.007987] ft260_raw_event: i2c resp: rep 0xde len 60
[ +0.007992] ft260_raw_event: i2c resp: rep 0xde len 60
[ +0.000206] ft260_xfer_status: bus_status 0x20, clock 100
Suggested-by: Enrik Berkhan <Enrik.Berkhan@inka.de>
Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid')
| -rw-r--r-- | drivers/hid/hid-ft260.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c index a354089bb747..91f9087e49dc 100644 --- a/drivers/hid/hid-ft260.c +++ b/drivers/hid/hid-ft260.c @@ -30,12 +30,19 @@ MODULE_PARM_DESC(debug, "Toggle FT260 debugging messages"); #define FT260_REPORT_MAX_LENGTH (64) #define FT260_I2C_DATA_REPORT_ID(len) (FT260_I2C_REPORT_MIN + (len - 1) / 4) + /* - * The input report format assigns 62 bytes for the data payload, but ft260 - * returns 60 and 2 in two separate transactions. To minimize transfer time - * in reading chunks mode, set the maximum read payload length to 60 bytes. - */ -#define FT260_RD_DATA_MAX (60) + * The ft260 input report format defines 62 bytes for the data payload, but + * when requested 62 bytes, the controller returns 60 and 2 in separate input + * reports. To achieve better performance with the multi-report read data + * transfers, we set the maximum read payload length to a multiple of 60. + * With a 100 kHz I2C clock, one 240 bytes read takes about 1/27 second, + * which is excessive; On the other hand, some higher layer drivers like at24 + * or optoe limit the i2c reads to 128 bytes. To not block other drivers out + * of I2C for potentially troublesome amounts of time, we select the maximum + * read payload length to be 180 bytes. +*/ +#define FT260_RD_DATA_MAX (180) #define FT260_WR_DATA_MAX (60) /* |