lkml.org 
[lkml]   [2016]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] driver: input :touchscreen : add Raydium I2C touch driver
From
Date
On May 22, 2016 2:32:59 AM PDT, "jeffrey.lin" <yajohn@gmail.com> wrote:
>Hi Dmitry:
>
>+static int raydium_i2c_read_message(struct i2c_client *client,
>+ u32 addr, void *data, size_t len)
>+{
>+ __be32 be_addr;
>+ size_t xfer_len;
>+ int error;
>+
>+ while (len) {
>+ xfer_len = min_t(size_t, len, RM_MAX_READ_SIZE);
>+
>+ be_addr = cpu_to_be32(addr);
>+
>+ error = raydium_i2c_send(client, RM_CMD_BANK_SWITCH,
>+ &be_addr, sizeof(be_addr));
>+ if (!error)
>+ error = raydium_i2c_read(client, (be_addr >> 24) & 0xff,
>+ data, xfer_len);
>+ if (error)
>+ return error;
>+
>+ len -= xfer_len;
>+ data += xfer_len;
>+ addr += xfer_len;
>+ }
>+
>+ return 0;
>+}
>I change access address method of touch MCU direct mode so that I can
>change raydium i2c driver as below.
>
>static int raydium_i2c_read_message(struct i2c_client *client,
> u32 addr, void *data, size_t len)
>{
> __le32 le_addr;
> size_t xfer_len;
> u32 shift_addr;
> int error;
>
> while (len) {
> xfer_len = min_t(size_t, len, RM_MAX_READ_SIZE);
>
> le_addr = cpu_to_le32(addr);
>
> shift_addr = le_addr >> 8;/*send the first 3rd byte addr.*/
> error = raydium_i2c_send(client, RM_CMD_BANK_SWITCH,
> &shift_addr, sizeof(le_addr));
> if (!error)/*read from last byte addr.*/
> error = raydium_i2c_read(client, le_addr & 0xff,
> data, xfer_len);
> if (error)
> return error;
>
> len -= xfer_len;
> data += xfer_len;
> addr += xfer_len;
> }
>
> return 0;
>}
>Is this okay? If okay, I will use this form update one new patch.

Why? It has the same problem - you can not do calculations on a variable in fixed endianness, because you do not know if your code will run on big or little endian CPU.

Doesn't my version of the code work?

>
>>> static int raydium_i2c_fw_write_page(struct i2c_client *client,
>>> u16 page_idx, const void *data, size_t len)
>>> {
>>> u8 buf[RM_BL_WRT_LEN];
>>> u8 pkg_idx = 1;
>>> size_t xfer_len;
>>> int error;
>>>
>>> while (len) {
>>> xfer_len = min_t(size_t, len, RM_BL_WRT_PKG_SIZE);
>>> buf[BL_HEADER] = RM_CMD_BOOT_PAGE_WRT;
>>> /*FIXME,Touch MCU need zero index as start page*/
>>> buf[BL_PAGE_STR] = page_idx ? 0xff : 0;
>>> buf[BL_PKG_IDX] = pkg_idx++;
>>>
>>> memcpy(&buf[BL_DATA_STR], data, xfer_len);
>>>
>>> if (len < RM_BL_WRT_PKG_SIZE) {
>>> buf[BL_PKG_IDX] = 4;
>
>>Why 4???
>4 is trigger index for write flash. Our page write size is 128 bytes,
>but in order to meet maximum I2C bus read/write byte limite and need
>fill full all pages of 128 bytes. So that I split 128 bytes to "4"
>section, and start burning flash if touch MCU get index "4".

That is not the best way of handling this. What if you get 2 blocks of RM_BL_WRT_PKG_SIZE data worth? You will never get to index 4. You should be tracking number of bytes received and do flash when you get full page.

Hi Jeffrey,
Thanks.

--
Dmitry

\
 
 \ /
  Last update: 2016-05-23 01:01    [W:0.265 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site