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Date: Wed, 14 Mar 2012 11:32:53 +0900
From: Joonyoung Shim <jy0922.shim@...sung.com>
To: Daniel Kurtz <djkurtz@...omium.org>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>,
Iiro Valkonen <iiro.valkonen@...el.com>,
Henrik Rydberg <rydberg@...omail.se>,
linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
Benson Leung <bleung@...omium.org>,
Yufeng Shen <miletus@...omium.org>
Subject: Re: [PATCH 18/20] Input: atmel_mxt_ts - read num messages,
then all messages
On 03/13/2012 09:04 PM, Daniel Kurtz wrote:
> Implement the MXT DMA method of reading messages.
> On an interrupt, the T44 report always contains the number of messages
> pending to be read. So, read 1 byte from T44 in 1 i2c transaction, then
> read the N pending messages in a second transaction.
My mXT224 chip datasheet hasn't T44 object, is it updated?
If not, need to consider chips which doesn't have T44 object.
> The end result is a much much faster read time for all pending messages.
> Using 400kHz i2c, it is possible to read 10 pending messages (e.g. for 10
> moving contatcts) in less than 2.8ms, which is well less than the typical
> 10-15ms update rate.
>
> Note: There is a possible optimization here. The T44 byte is guaranteed
> to always be right before the T5 address. Thus, it should be possible
> to always fetch the T44 message count and the first message in a single
> transaction. This would eliminate the overhead of a second complete read
> transaction for the case where there is only a single pending message.
> (This is actually the most common case, for instance with just 1-contact
> on the device touch surface). This optimization, however, is not done in
> this patch.
>
> Signed-off-by: Daniel Kurtz<djkurtz@...omium.org>
> ---
> drivers/input/touchscreen/atmel_mxt_ts.c | 92 ++++++++++++++++++++----------
> 1 files changed, 61 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 88a474e..dafc030 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -251,8 +251,10 @@ struct mxt_data {
> unsigned int max_y;
>
> /* Cached parameters from object table */
> + u16 T5_address;
> u8 T9_reportid_min;
> u8 T9_reportid_max;
> + u16 T44_address;
> };
>
> static bool mxt_object_readable(unsigned int type)
> @@ -486,21 +488,6 @@ static int mxt_read_object(struct mxt_data *data, struct mxt_object *object,
> val);
> }
>
> -static int mxt_read_message(struct mxt_data *data,
> - struct mxt_message *message)
> -{
> - struct mxt_object *object;
> - u16 reg;
> -
> - object = mxt_get_object(data, MXT_GEN_MESSAGE_T5);
> - if (!object)
> - return -EINVAL;
> -
> - reg = object->start_address;
> - return mxt_read_reg(data->client, reg, sizeof(struct mxt_message),
> - message);
> -}
> -
> static int mxt_write_object(struct mxt_data *data,
> u8 type, u8 offset, u8 val)
> {
> @@ -515,6 +502,19 @@ static int mxt_write_object(struct mxt_data *data,
> return mxt_write_reg(data->client, reg + offset, 1,&val);
> }
>
> +static int mxt_read_num_messages(struct mxt_data *data, u8 *count)
> +{
> + /* TODO: Optimization: read first message along with message count */
> + return mxt_read_reg(data->client, data->T44_address, 1, count);
> +}
> +
> +static int mxt_read_messages(struct mxt_data *data, u8 count,
> + struct mxt_message *messages)
> +{
> + return mxt_read_reg(data->client, data->T5_address,
> + sizeof(struct mxt_message) * count, messages);
> +}
> +
> static void mxt_input_touchevent(struct mxt_data *data,
> struct mxt_message *message)
> {
> @@ -575,26 +575,50 @@ static void mxt_input_touchevent(struct mxt_data *data,
> input_sync(input_dev);
> }
>
> -static irqreturn_t mxt_interrupt(int irq, void *dev_id)
> +static int mxt_proc_messages(struct mxt_data *data, u8 count)
> {
> - struct mxt_data *data = dev_id;
> - struct mxt_message message;
> struct device *dev =&data->client->dev;
> + struct mxt_message messages[count], *msg;
> + int ret;
>
> - do {
> - if (mxt_read_message(data,&message)) {
> - dev_err(dev, "Failed to read message\n");
> - goto end;
> - }
> + ret = mxt_read_messages(data, count, messages);
> + if (ret) {
> + dev_err(dev, "Failed to read %u messages (%d).\n", count, ret);
> + return ret;
> + }
> +
> + for (msg = messages; msg< &messages[count]; msg++) {
> + mxt_dump_message(dev, msg);
> +
> + if (msg->reportid>= data->T9_reportid_min&&
> + msg->reportid<= data->T9_reportid_max)
> + mxt_input_touchevent(data, msg);
> + }
> +
> + return 0;
> +}
> +
> +static int mxt_handle_messages(struct mxt_data *data)
> +{
> + struct device *dev =&data->client->dev;
> + int ret;
> + u8 count;
>
> - if (message.reportid>= data->T9_reportid_min&&
> - message.reportid<= data->T9_reportid_max)
> - mxt_input_touchevent(data,&message);
> - else
> - mxt_dump_message(dev,&message);
> - } while (message.reportid != 0xff);
> + ret = mxt_read_num_messages(data,&count);
> + if (ret) {
> + dev_err(dev, "Failed to read message count (%d).\n", ret);
> + return ret;
> + }
>
> -end:
> + if (count> 0)
> + ret = mxt_proc_messages(data, count);
> +
> + return ret;
> +}
> +
> +static irqreturn_t mxt_interrupt(int irq, void *dev_id)
> +{
> + mxt_handle_messages(dev_id);
> return IRQ_HANDLED;
> }
>
> @@ -642,7 +666,7 @@ static int mxt_make_highchg(struct mxt_data *data)
>
> /* Read dummy message to make high CHG pin */
> do {
> - error = mxt_read_message(data,&message);
> + error = mxt_read_messages(data, 1,&message);
> if (error)
> return error;
> } while (message.reportid != 0xff&& --count);
> @@ -743,11 +767,17 @@ static int mxt_get_object_table(struct mxt_data *data)
>
> /* Save data for objects used when processing interrupts */
> switch (object->type) {
> + case MXT_GEN_MESSAGE_T5:
> + data->T5_address = object->start_address;
> + break;
> case MXT_TOUCH_MULTI_T9:
> data->T9_reportid_max = object->max_reportid;
> data->T9_reportid_min = data->T9_reportid_max -
> object->num_report_ids + 1;
> break;
> + case MXT_SPT_MESSAGECOUNT_T44:
> + data->T44_address = object->start_address;
> + break;
> }
> }
>
--
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