| Message ID | 20220928144854.5580-3-michael.zaidman@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | HID: ft260: fixes and performance improvements | expand |
From: Michael Zaidman > Sent: 28 September 2022 15:49 > > The patch improves i2c writing performance by about 30 percent by revising > the sleep time in the ft260_hid_output_report_check_status() in the > following ways: Spinning in kernel for several milliseconds isn't friendly at all. David > > 1. Reduce the sleep time and start to poll earlier: > > Before: > $ sudo ./i2cperf -f 2 -o 2 -s 32 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 40510 80 256 8 32 > > After: > $ sudo ./i2cperf -f 2 -o 2 -s 32 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 52584 80 256 8 32 > > 2. Do not sleep when the calculated sleep time is below 2 ms: > > Before: > $ sudo ./i2cperf -f 2 -o 2 -s 16 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 26707 73 256 16 16 > > After: > $ sudo ./i2cperf -f 2 -o 2 -s 16 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 37034 73 256 16 16 > > Link to the i2cperf - https://github.com/MichaelZaidman/i2cperf > > Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com> > Tested-by: Guillaume Champagne <champagne.guillaume.c@gmail.com> > --- > drivers/hid/hid-ft260.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c > index a35201d68b15..44106cadd746 100644 > --- a/drivers/hid/hid-ft260.c > +++ b/drivers/hid/hid-ft260.c > @@ -345,7 +345,7 @@ static int ft260_hid_output_report(struct hid_device *hdev, u8 *data, > static int ft260_hid_output_report_check_status(struct ft260_device *dev, > u8 *data, int len) > { > - int ret, usec, try = 3; > + int ret, usec, try = 100; > struct hid_device *hdev = dev->hdev; > > ret = ft260_hid_output_report(hdev, data, len); > @@ -356,10 +356,14 @@ static int ft260_hid_output_report_check_status(struct ft260_device *dev, > return ret; > } > > - /* transfer time = 1 / clock(KHz) * 10 bits * bytes */ > - usec = 10000 / dev->clock * len; > - usleep_range(usec, usec + 100); > - ft260_dbg("wait %d usec, len %d\n", usec, len); > + /* transfer time = 1 / clock(KHz) * 9 bits * bytes */ > + usec = len * 9000 / dev->clock; > + if (usec > 2000) { > + usec -= 1500; > + usleep_range(usec, usec + 100); > + ft260_dbg("wait %d usec, len %d\n", usec, len); > + } > + > do { > ret = ft260_xfer_status(dev); > if (ret != -EAGAIN) > -- > 2.34.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c index a35201d68b15..44106cadd746 100644 --- a/drivers/hid/hid-ft260.c +++ b/drivers/hid/hid-ft260.c @@ -345,7 +345,7 @@ static int ft260_hid_output_report(struct hid_device *hdev, u8 *data, static int ft260_hid_output_report_check_status(struct ft260_device *dev, u8 *data, int len) { - int ret, usec, try = 3; + int ret, usec, try = 100; struct hid_device *hdev = dev->hdev; ret = ft260_hid_output_report(hdev, data, len); @@ -356,10 +356,14 @@ static int ft260_hid_output_report_check_status(struct ft260_device *dev, return ret; } - /* transfer time = 1 / clock(KHz) * 10 bits * bytes */ - usec = 10000 / dev->clock * len; - usleep_range(usec, usec + 100); - ft260_dbg("wait %d usec, len %d\n", usec, len); + /* transfer time = 1 / clock(KHz) * 9 bits * bytes */ + usec = len * 9000 / dev->clock; + if (usec > 2000) { + usec -= 1500; + usleep_range(usec, usec + 100); + ft260_dbg("wait %d usec, len %d\n", usec, len); + } + do { ret = ft260_xfer_status(dev); if (ret != -EAGAIN)
The patch improves i2c writing performance by about 30 percent by revising the sleep time in the ft260_hid_output_report_check_status() in the following ways: 1. Reduce the sleep time and start to poll earlier: Before: $ sudo ./i2cperf -f 2 -o 2 -s 32 -r 0-0xff 13 0x51 -S Fill block with increment via i2ctransfer by chunks ------------------------------------------------------------------- data rate(bps) efficiency(%) data size(B) total IOs IO size(B) ------------------------------------------------------------------- 40510 80 256 8 32 After: $ sudo ./i2cperf -f 2 -o 2 -s 32 -r 0-0xff 13 0x51 -S Fill block with increment via i2ctransfer by chunks ------------------------------------------------------------------- data rate(bps) efficiency(%) data size(B) total IOs IO size(B) ------------------------------------------------------------------- 52584 80 256 8 32 2. Do not sleep when the calculated sleep time is below 2 ms: Before: $ sudo ./i2cperf -f 2 -o 2 -s 16 -r 0-0xff 13 0x51 -S Fill block with increment via i2ctransfer by chunks ------------------------------------------------------------------- data rate(bps) efficiency(%) data size(B) total IOs IO size(B) ------------------------------------------------------------------- 26707 73 256 16 16 After: $ sudo ./i2cperf -f 2 -o 2 -s 16 -r 0-0xff 13 0x51 -S Fill block with increment via i2ctransfer by chunks ------------------------------------------------------------------- data rate(bps) efficiency(%) data size(B) total IOs IO size(B) ------------------------------------------------------------------- 37034 73 256 16 16 Link to the i2cperf - https://github.com/MichaelZaidman/i2cperf Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com> Tested-by: Guillaume Champagne <champagne.guillaume.c@gmail.com> --- drivers/hid/hid-ft260.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)