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SubjectRe: [PATCH 18/21 v5] Input: atmel_mxt_ts - cache T9 reportid range when reading object table
Hi Daniel,

> Streamline interrupt processing by caching the T9 reportid range when
> first reading the object table.
>
> In the process, refactor reading the object descriptor table.
> First, since the object_table entries are now exactly the same layout
> in device memory and in the driver, allocate an appropriately sized
> array and fetch the entire table directly into it in a single i2c
> transaction. Since a 6 byte table object requires 10 bytes to read,
> doing this dramatically reduces overhead.
>
> Note: The cached T9 reportid's are initialized to 0, which is an invalid
> reportid. Thus, the checks in the interrupt handler will always fail for
> devices that do not support the T9 object. Therefore, after doing a
> firmware update, the old object table is destroyed and all cached object
> values are reset to 0, before reading the new object table, in case
> the new firmware does not have the old objects.
>
> This patch tested on an MXT224E.
>
> Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
> ---
> drivers/input/touchscreen/atmel_mxt_ts.c | 80 +++++++++++++++++-------------
> 1 files changed, 45 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 7b042e5..4da12a9 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -227,13 +227,10 @@ struct mxt_info {
> struct mxt_object {
> u8 type;
> u16 start_address;
> - u8 size;
> - u8 instances;
> + u8 size; /* Size of each instance - 1 */
> + u8 instances; /* Number of instances - 1 */
> u8 num_report_ids;
> -
> - /* to map object and message */
> - u8 max_reportid;
> -};
> +} __packed;
>
> struct mxt_message {
> u8 reportid;
> @@ -251,6 +248,10 @@ struct mxt_data {
> unsigned int irq;
> unsigned int max_x;
> unsigned int max_y;
> +
> + /* Cached parameters from object table */
> + u8 T9_reportid_min;
> + u8 T9_reportid_max;
> };
>
> static bool mxt_object_readable(unsigned int type)
> @@ -458,13 +459,6 @@ static int mxt_write_reg(struct i2c_client *client, u16 reg, u8 val)
> return __mxt_write_reg(client, reg, 1, &val);
> }
>
> -static int mxt_read_object_table(struct i2c_client *client,
> - u16 reg, u8 *object_buf)
> -{
> - return __mxt_read_reg(client, reg, MXT_OBJECT_SIZE,
> - object_buf);
> -}
> -
> static struct mxt_object *
> mxt_get_object(struct mxt_data *data, u8 type)
> {
> @@ -563,7 +557,6 @@ static irqreturn_t mxt_interrupt(int irq, void *dev_id)
> {
> struct mxt_data *data = dev_id;
> struct mxt_message message;
> - struct mxt_object *object;
> struct device *dev = &data->client->dev;
> int id;
> u8 reportid;
> @@ -578,13 +571,8 @@ static irqreturn_t mxt_interrupt(int irq, void *dev_id)
>
> reportid = message.reportid;
>
> - /* whether reportid is thing of MXT_TOUCH_MULTI_T9 */
> - object = mxt_get_object(data, MXT_TOUCH_MULTI_T9);
> - if (!object)
> - goto end;
> -
> - max_reportid = object->max_reportid;
> - min_reportid = max_reportid - object->num_report_ids + 1;
> + max_reportid = data->T9_reportid_max;
> + min_reportid = data->T9_reportid_min;
> id = reportid - min_reportid;
>
> if (reportid >= min_reportid && reportid <= max_reportid)
> @@ -719,30 +707,49 @@ static int mxt_get_info(struct mxt_data *data)
>
> static int mxt_get_object_table(struct mxt_data *data)
> {
> + struct i2c_client *client = data->client;
> + size_t table_size;
> int error;
> int i;
> - u16 reg;
> - u8 reportid = 0;
> - u8 buf[MXT_OBJECT_SIZE];
> + u8 reportid;
>
> + table_size = data->info.object_num * sizeof(struct mxt_object);
> + error = __mxt_read_reg(client, MXT_OBJECT_START, table_size,
> + data->object_table);
> + if (error) {
> + kfree(data->object_table);
> + data->object_table = NULL;
> + return error;

Freeing the object table here does not look right. Either free it in
mxt_initialize() or move the allocation into this function as well.

> + }
> +
> + /* Valid Report IDs start counting from 1 */
> + reportid = 1;
> for (i = 0; i < data->info.object_num; i++) {
> struct mxt_object *object = data->object_table + i;
> + u8 min_id, max_id;
>
> - reg = MXT_OBJECT_START + MXT_OBJECT_SIZE * i;
> - error = mxt_read_object_table(data->client, reg, buf);
> - if (error)
> - return error;
> -
> - object->type = buf[0];
> - object->start_address = (buf[2] << 8) | buf[1];
> - object->size = buf[3];
> - object->instances = buf[4];
> - object->num_report_ids = buf[5];
> + le16_to_cpus(&object->start_address);
>
> if (object->num_report_ids) {
> + min_id = reportid;
> reportid += object->num_report_ids *
> (object->instances + 1);
> - object->max_reportid = reportid;
> + max_id = reportid - 1;
> + } else {
> + min_id = 0;
> + max_id = 0;
> + }
> +
> + dev_info(&data->client->dev,
> + "Type %2d Start %3d Size %3d Instances %2d ReportIDs %3u : %3u\n",
> + object->type, object->start_address, object->size + 1,
> + object->instances + 1, min_id, max_id);

On a normal boot, how many lines of output does this driver generate?

> +
> + switch (object->type) {
> + case MXT_TOUCH_MULTI_T9:
> + data->T9_reportid_min = min_id;
> + data->T9_reportid_max = max_id;
> + break;
> }
> }
>
> @@ -995,8 +1002,11 @@ static ssize_t mxt_update_fw_store(struct device *dev,
> /* Wait for reset */
> msleep(MXT_FWRESET_TIME);
>
> + /* Destroy old object table and any cached fields */
> kfree(data->object_table);
> data->object_table = NULL;
> + data->T9_reportid_min = 0;
> + data->T9_reportid_max = 0;
>
> mxt_initialize(data);
> }
> --
> 1.7.7.3
>

Thanks,
Henrik


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