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Message-ID: <CAGS+omAPBSqs9BZQJ4dLYADE=htZdXOZkAne=eD_4GNLmoUv4w@mail.gmail.com>
Date: Wed, 14 Mar 2012 11:13:58 +0800
From: Daniel Kurtz <djkurtz@...omium.org>
To: Joonyoung Shim <jy0922.shim@...sung.com>
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 Wed, Mar 14, 2012 at 10:32 AM, Joonyoung Shim
<jy0922.shim@...sung.com> wrote:
> 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.
I could consider merging the use of T44 with the older 'check reportid
0xff' method, but would require help verifying the change with
hardware that doesn't have T44.
Does anybody out there have such hardware and is willing to test?
Thanks,
-Daniel
>
>> 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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