| Message ID | 1616084743-112402-2-git-send-email-zhouyanjie@wanyeetech.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | I2C: JZ4780: Fix bug for Ingenic X1000. | expand |
On Fri, Mar 19, 2021 at 12:25:43AM +0800, 周琰杰 (Zhou Yanjie) wrote: > Only send "X1000_I2C_DC_STOP" when last byte, or it will cause > error when I2C write operation. > > Fixes: 21575a7a8d4c ("I2C: JZ4780: Add support for the X1000.") > > Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> > --- > drivers/i2c/busses/i2c-jz4780.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > <formletter> This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly. </formletter>
Hi Wolfram, Sorry, please forgive my carefulness, I wrongly sent the version that did not clean up, resulting in missing the reporter's information and some errors in formats. On 2021/3/19 上午1:06, Wolfram Sang wrote: > On Fri, Mar 19, 2021 at 12:25:43AM +0800, 周琰杰 (Zhou Yanjie) wrote: >> Only send "X1000_I2C_DC_STOP" when last byte, or it will cause >> error when I2C write operation. > Any write operation? I wonder then why nobody noticed before? The standard I2C communication should look like this: Read: device_addr + w, reg_addr, device_addr + r, data; Write: device_addr + w, reg_addr, data; But without this patch, it looks like this: Read: device_addr + w, reg_addr, device_addr + r, data; Write: device_addr + w, reg_addr, device_addr + w, data; This is clearly not correct. When I added support for X1000 to this driver, the hardware used was CU1000-Neo. On this hardware, there was an ADS7830 that communicated through I2C, but the operation of ADS7830 only involved read operations, so I was at that time failed to realize the problem with the write operation. In addition, because X1000 did not implement relatively complete support in the mainline until the second half of 2020, there are still a large number of users who are still using the old SDK (kernel 3.10 and kernel4.4) provided by Ingenics, which may also be indirectly delayed exposure of this problem. >> - while ((i2c_sta & JZ4780_I2C_STA_TFNF) && >> - (i2c->wt_len > 0)) { >> + while ((i2c_sta & JZ4780_I2C_STA_TFNF) && (i2c->wt_len > 0)) { > This is a cosmetic change only IIUC. Shouldn't be in a bugfix. > My fault, I will remove it in the next version. Thanks and best regards!
Hi Wolfram, On 2021/3/31 下午3:18, Wolfram Sang wrote: > Hi, > >>> Any write operation? I wonder then why nobody noticed before? >> >> The standard I2C communication should look like this: >> >> Read: >> >> device_addr + w, reg_addr, device_addr + r, data; >> >> Write: >> >> device_addr + w, reg_addr, data; >> >> >> But without this patch, it looks like this: >> >> Read: >> >> device_addr + w, reg_addr, device_addr + r, data; >> >> Write: >> >> device_addr + w, reg_addr, device_addr + w, data; >> >> This is clearly not correct. > Thanks for the additional information! I understand now. I added a bit > of this to the commit message of v2 to explain the situation. > Thanks! Best regards!
diff --git a/drivers/i2c/busses/i2c-jz4780.c b/drivers/i2c/busses/i2c-jz4780.c index 8509c5f..1ad093a 100644 --- a/drivers/i2c/busses/i2c-jz4780.c +++ b/drivers/i2c/busses/i2c-jz4780.c @@ -520,13 +520,12 @@ static irqreturn_t jz4780_i2c_irq(int irqno, void *dev_id) i2c_sta = jz4780_i2c_readw(i2c, JZ4780_I2C_STA); - while ((i2c_sta & JZ4780_I2C_STA_TFNF) && - (i2c->wt_len > 0)) { + while ((i2c_sta & JZ4780_I2C_STA_TFNF) && (i2c->wt_len > 0)) { i2c_sta = jz4780_i2c_readw(i2c, JZ4780_I2C_STA); data = *i2c->wbuf; data &= ~JZ4780_I2C_DC_READ; - if ((!i2c->stop_hold) && (i2c->cdata->version >= - ID_X1000)) + if ((i2c->wt_len == 1) && (!i2c->stop_hold) && + (i2c->cdata->version >= ID_X1000)) data |= X1000_I2C_DC_STOP; jz4780_i2c_writew(i2c, JZ4780_I2C_DC, data); i2c->wbuf++;
Only send "X1000_I2C_DC_STOP" when last byte, or it will cause error when I2C write operation. Fixes: 21575a7a8d4c ("I2C: JZ4780: Add support for the X1000.") Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com> --- drivers/i2c/busses/i2c-jz4780.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)