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Message-ID: <7c57ae66-41ad-aba3-a466-6c6f79652638@mentor.com>
Date: Sat, 12 Sep 2020 09:50:22 +0900
From: "Wang, Jiada" <jiada_wang@...tor.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
CC: "nick@...anahar.org" <nick@...anahar.org>,
"dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Andrew_Gabbasov@...tor.com" <Andrew_Gabbasov@...tor.com>,
"erosca@...adit-jv.com" <erosca@...adit-jv.com>,
"digetx@...il.com" <digetx@...il.com>
Subject: Re: [PATCH v2 1/1] Input: atmel_mxt_ts - implement I2C retries
Hi Andy
Thanks for your comment
On 2020/09/06 3:02, Andy Shevchenko wrote:
>
>
> On Thursday, September 3, 2020, Jiada Wang <jiada_wang@...tor.com
> <mailto:jiada_wang@...tor.com>> wrote:
>
> From: Nick Dyer <nick.dyer@...ev.co.uk <mailto:nick.dyer@...ev.co.uk>>
>
> Some maXTouch chips (eg mXT1386) will not respond on the first I2C
> request
> when they are in a sleep state. It must be retried after a delay for the
> chip to wake up.
>
> Signed-off-by: Nick Dyer <nick.dyer@...ev.co.uk
> <mailto:nick.dyer@...ev.co.uk>>
> Acked-by: Yufeng Shen <miletus@...omium.org
> <mailto:miletus@...omium.org>>
>
>
> (cherry picked from ndyer/linux/for-upstream commit
> 63fd7a2cd03c3a572a5db39c52f4856819e1835d)
>
>
> It’s a noise for upstream.
>
sure, I will remove it
> [gdavis: Forward port and fix conflicts.]
> Signed-off-by: George G. Davis <george_davis@...tor.com
> <mailto:george_davis@...tor.com>>
> [jiada: return exact errno when i2c_transfer & i2c_master_send fails]
> Signed-off-by: Jiada Wang <jiada_wang@...tor.com
> <mailto:jiada_wang@...tor.com>>
> ---
> drivers/input/touchscreen/atmel_mxt_ts.c | 45 ++++++++++++++++--------
> 1 file changed, 30 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c
> b/drivers/input/touchscreen/atmel_mxt_ts.c
> index a2189739e30f..5d4cb15d21dc 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -196,6 +196,7 @@ enum t100_type {
> #define MXT_CRC_TIMEOUT 1000 /* msec */
> #define MXT_FW_RESET_TIME 3000 /* msec */
> #define MXT_FW_CHG_TIMEOUT 300 /* msec */
> +#define MXT_WAKEUP_TIME 25 /* msec */
>
>
> Can we simple add _MS unit suffix to the definition?
As Dmitry commented, I'd like to keep it as-is, probably a separate
patch to update all these together.
>
>
> /* Command to unlock bootloader */
> #define MXT_UNLOCK_CMD_MSB 0xaa
> @@ -626,6 +627,7 @@ static int __mxt_read_reg(struct i2c_client *client,
> struct i2c_msg xfer[2];
> u8 buf[2];
> int ret;
> + bool retry = false;
>
>
> Keep this ordered by length.
I will move "retry" upper.
>
>
> buf[0] = reg & 0xff;
> buf[1] = (reg >> 8) & 0xff;
> @@ -642,17 +644,22 @@ static int __mxt_read_reg(struct i2c_client
> *client,
> xfer[1].len = len;
> xfer[1].buf = val;
>
> - ret = i2c_transfer(client->adapter, xfer, 2);
> - if (ret == 2) {
> - ret = 0;
> - } else {
> - if (ret >= 0)
> - ret = -EIO;
> - dev_err(&client->dev, "%s: i2c transfer failed (%d)\n",
> - __func__, ret);
> +retry_read:
> + ret = i2c_transfer(client->adapter, xfer, ARRAY_SIZE(xfer));
> + if (ret != ARRAY_SIZE(xfer)) {
> + if (!retry) {
>
>
> Why not positive conditional?
to me, it's not much different either positive or negative conditional,
can you elaborate more about this?
>
> + dev_dbg(&client->dev, "%s: i2c retry\n",
> __func__);
>
>
> __func__ is redundant for dev_dbg().
>
> + msleep(MXT_WAKEUP_TIME);
> + retry = true;
> + goto retry_read;
>
> + } else {
>
>
> Redundant in either case of conditional. Allows to drop indentation level.
I will remove the redundant conditional
Thanks,
Jiada
>
> + dev_err(&client->dev, "%s: i2c transfer
> failed (%d)\n",
> + __func__, ret);
> + return ret < 0 ? ret : -EIO;
> + }
> }
>
> - return ret;
> + return 0;
> }
>
>
> Same comments about below.
>
> static int __mxt_write_reg(struct i2c_client *client, u16 reg, u16
> len,
> @@ -661,6 +668,7 @@ static int __mxt_write_reg(struct i2c_client
> *client, u16 reg, u16 len,
> u8 *buf;
> size_t count;
> int ret;
> + bool retry = false;
>
> count = len + 2;
> buf = kmalloc(count, GFP_KERNEL);
> @@ -671,14 +679,21 @@ static int __mxt_write_reg(struct i2c_client
> *client, u16 reg, u16 len,
> buf[1] = (reg >> 8) & 0xff;
> memcpy(&buf[2], val, len);
>
> +retry_write:
> ret = i2c_master_send(client, buf, count);
> - if (ret == count) {
> - ret = 0;
> + if (ret != count) {
> + if (!retry) {
> + dev_dbg(&client->dev, "%s: i2c retry\n",
> __func__);
> + msleep(MXT_WAKEUP_TIME);
> + retry = true;
> + goto retry_write;
> + } else {
> + dev_err(&client->dev, "%s: i2c send failed
> (%d)\n",
> + __func__, ret);
> + ret = ret < 0 ? ret : -EIO;
> + }
> } else {
> - if (ret >= 0)
> - ret = -EIO;
> - dev_err(&client->dev, "%s: i2c send failed (%d)\n",
> - __func__, ret);
> + ret = 0;
> }
>
> kfree(buf);
> --
> 2.17.1
>
>
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
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