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Date: Tue, 14 Jan 2014 00:26:47 -0800
From: Christopher Heiny <cheiny@...aptics.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
CC: Andrew Duggan <aduggan@...aptics.com>,
Vincent Huang <vincent.huang@...synaptics.com>,
Vivian Ly <vly@...aptics.com>,
Daniel Rosenberg <daniel.rosenberg@...aptics.com>,
Linus Walleij <linus.walleij@...ricsson.com>,
Benjamin Tissoires <benjamin.tissoires@...hat.com>,
Linux Input <linux-input@...r.kernel.org>,
Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] Input: synaptics-rmi4 - switch to using i2c_transfer()
On 01/09/2014 11:44 PM, Dmitry Torokhov wrote:
> Instead of using 2 separate transactions when reading from the device let's
> use i2c_transfer. Because we now have single point of failure I had to
> change how we collect statistics. I elected to drop control data from the
> stats and only track number of bytes read/written for the device data.
>
> Also, since we are not prepared to deal with short reads and writes change
> read_block_data and write_block_data to indicate error if we detect short
> transfers.
>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
> drivers/input/rmi4/rmi_i2c.c | 71 ++++++++++++++++++++++++--------------------
> 1 file changed, 39 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/input/rmi4/rmi_i2c.c b/drivers/input/rmi4/rmi_i2c.c
> index c176218..51f5bc8 100644
> --- a/drivers/input/rmi4/rmi_i2c.c
> +++ b/drivers/input/rmi4/rmi_i2c.c
> @@ -57,22 +57,17 @@ struct rmi_i2c_xport {
> */
> static int rmi_set_page(struct rmi_i2c_xport *rmi_i2c, u8 page)
> {
> - struct rmi_transport_dev *xport = &rmi_i2c->xport;
> struct i2c_client *client = rmi_i2c->client;
> u8 txbuf[2] = {RMI_PAGE_SELECT_REGISTER, page};
> int retval;
>
> - dev_dbg(&client->dev, "writes 3 bytes: %02x %02x\n",
> - txbuf[0], txbuf[1]);
> - xport->stats.tx_count++;
> - xport->stats.tx_bytes += sizeof(txbuf);
> retval = i2c_master_send(client, txbuf, sizeof(txbuf));
> if (retval != sizeof(txbuf)) {
> - xport->stats.tx_errs++;
> dev_err(&client->dev,
> "%s: set page failed: %d.", __func__, retval);
> return (retval < 0) ? retval : -EIO;
> }
> +
> rmi_i2c->page = page;
> return 0;
> }
> @@ -107,22 +102,27 @@ static int rmi_i2c_write_block(struct rmi_transport_dev *xport, u16 addr,
>
> if (RMI_I2C_PAGE(addr) != rmi_i2c->page) {
> retval = rmi_set_page(rmi_i2c, RMI_I2C_PAGE(addr));
> - if (retval < 0)
> + if (retval)
> goto exit;
> }
>
> + retval = i2c_master_send(client, rmi_i2c->tx_buf, tx_size);
> + if (retval == tx_size)
> + retval = 0;
> + else if (retval >= 0)
> + retval = -EIO;
> +
> +exit:
> dev_dbg(&client->dev,
> - "writes %zd bytes at %#06x: %*ph\n", len, addr, (int)len, buf);
> + "write %zd bytes at %#06x: %d (%*ph)\n",
> + len, addr, retval, (int)len, buf);
>
> xport->stats.tx_count++;
> - xport->stats.tx_bytes += tx_size;
> - retval = i2c_master_send(client, rmi_i2c->tx_buf, tx_size);
> - if (retval < 0)
> + if (retval)
> xport->stats.tx_errs++;
> else
> - retval--; /* don't count the address byte */
> + xport->stats.tx_bytes += len;
>
> -exit:
> mutex_unlock(&rmi_i2c->page_mutex);
> return retval;
> }
> @@ -133,40 +133,47 @@ static int rmi_i2c_read_block(struct rmi_transport_dev *xport, u16 addr,
> struct rmi_i2c_xport *rmi_i2c =
> container_of(xport, struct rmi_i2c_xport, xport);
> struct i2c_client *client = rmi_i2c->client;
> - u8 txbuf[1] = {addr & 0xff};
> + u8 addr_offset = addr & 0xff;
> int retval;
> + struct i2c_msg msgs[] = {
> + {
> + .addr = client->addr,
> + .len = sizeof(addr_offset),
> + .buf = &addr_offset,
> + },
> + {
> + .addr = client->addr,
> + .flags = I2C_M_RD,
> + .len = len,
> + .buf = buf,
> + },
> + };
>
> mutex_lock(&rmi_i2c->page_mutex);
>
> if (RMI_I2C_PAGE(addr) != rmi_i2c->page) {
> retval = rmi_set_page(rmi_i2c, RMI_I2C_PAGE(addr));
> - if (retval < 0)
> + if (retval)
> goto exit;
> }
>
> - dev_dbg(&client->dev, "writes 1 bytes: %02x\n", txbuf[0]);
> + retval = i2c_transfer(client->adapter, msgs, sizeof(msgs));
> + if (retval == sizeof(msgs))
I think this should be:
retval = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
if (retval == ARRAY_SIZE(msgs))
At least, that change resolved some random misbehaviors, including
kernel panics.
> + retval = 0; /* success */
> + else if (retval >= 0)
> + retval = -EIO;
>
> - xport->stats.tx_count++;
> - xport->stats.tx_bytes += sizeof(txbuf);
> - retval = i2c_master_send(client, txbuf, sizeof(txbuf));
> - if (retval != sizeof(txbuf)) {
> - xport->stats.tx_errs++;
> - retval = (retval < 0) ? retval : -EIO;
> - goto exit;
> - }
> +exit:
> + dev_dbg(&client->dev,
> + "read %zd bytes at %#06x: %d (%*ph)\n",
> + len, addr, retval, (int)len, buf);
>
> xport->stats.rx_count++;
> - xport->stats.rx_bytes += len;
> -
> - retval = i2c_master_recv(client, buf, len);
> - if (retval < 0)
> + if (retval)
> xport->stats.rx_errs++;
> else
> - dev_dbg(&client->dev,
> - "read %zd bytes at %#06x: %*ph\n",
> - len, addr, (int)len, buf);
> + xport->stats.rx_bytes += len;
>
> -exit:
> mutex_unlock(&rmi_i2c->page_mutex);
> return retval;
> }
>
--
Christopher Heiny
Senior Staff Firmware Engineer
Synaptics Incorporated
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