On Wed, May 25, 2022 at 11:44:09AM -0400, Guillaume Champagne wrote:

Le mer. 25 mai 2022 à 03:48, Michael Zaidman
[off-list ref] a écrit :

quoted

To support longer than one HID report size write, the driver splits a single
i2c message data payload into multiple i2c messages of HID report size.
However, it does not replicate the offset bytes within the EEPROM chip in
every consequent HID report because it is not and should not be aware of
the EEPROM type. It breaks the i2c write message integrity and causes the
EEPROM device not to acknowledge the second HID report keeping the i2c bus
busy until the ft260 controller reports failure.

I tested this whole patchset and it resolves the issue I raised
https://patchwork.kernel.org/project/linux-input/patch/20220524192422.13967-1-champagne.guillaume.c@gmail.com/,
thanks.

Much appreciated!
I will add your tested-by in the second version of the patchset.

quoted

This patch preserves the i2c write message integrity by manipulating the
i2c flag bits across multiple HID reports to be seen by the EEPROM device
as a single i2c write transfer.

Before:

$ sudo ./i2cperf -f 2 -o 2 -s 64 -r 0-0xff 13 0x51 -S
Error: Sending messages failed: Input/output error

[  +3.667741] ft260_i2c_write: rep 0xde addr 0x51 off 0 len 60 d[0] 0x0
[  +0.007330] ft260_hid_output_report_check_status: wait 6400 usec, len 64
[  +0.000203] ft260_xfer_status: bus_status 0x40, clock 100
[  +0.000001] ft260_i2c_write: rep 0xd1 addr 0x51 off 60 len 6 d[0] 0x0
[  +0.002337] ft260_hid_output_report_check_status: wait 1000 usec, len 10
[  +0.000157] ft260_xfer_status: bus_status 0x2e, clock 100
[  +0.000241] ft260_i2c_reset: done
[  +0.000003] ft260 0003:0403:6030.000E: ft260_i2c_write: failed to start transfer, ret -5

After:

$ sudo ./i2cperf -f 2 -o 2 -s 128 -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)
  -------------------------------------------------------------------
  58986           86             256           2           128

Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
---
 drivers/hid/hid-ft260.c | 45 ++++++++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 44106cadd746..bfda5b191a3a 100644
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c

@@ -378,41 +378,50 @@ static int ft260_hid_output_report_check_status(struct ft260_device *dev,
 }

 static int ft260_i2c_write(struct ft260_device *dev, u8 addr, u8 *data,
-                          int data_len, u8 flag)
+                          int len, u8 flag)
 {
-       int len, ret, idx = 0;
+       int ret, wr_len, idx = 0;
+       bool first = true;
        struct hid_device *hdev = dev->hdev;
        struct ft260_i2c_write_request_report *rep =
                (struct ft260_i2c_write_request_report *)dev->write_buf;

        do {
-               if (data_len <= FT260_WR_DATA_MAX)
-                       len = data_len;
-               else
-                       len = FT260_WR_DATA_MAX;
+               rep->flag = 0;
+               if (first) {
+                       rep->flag = FT260_FLAG_START;

I feel like multi packet transactions must still honor flag sent to
ft20_i2c_write. This adds a START even if ft260_i2c_write is called
with FT260_FLAG_START_REPEATED or FT260_FLAG_NONE.

We use the FT260_FLAG_START_REPEATED to precede the Read message following
the Write message in the i2c combined transaction. Am I missing any i2c
protocol case using the Repeated Start in the Write path?

The FT260_FLAG_NONE should not be passed into the ft20_i2c_write as well.

So, we can keep it simple.