感觉realtouch的spi_flash_w25qxx的write函数存在bug[已修正]

发布于 2013-07-28 12:33:26 浏览：6537 订阅该版

首先看w25qxx_page_write函数：
```uint32_t w25qxx_page_write(uint32_t page, const uint8_t * buffer, uint32_t size)
{
    uint32_t index;
    uint8_t send_buffer[4];

RT_ASSERT((page&0xFF) == 0);

send_buffer[0] = CMD_WREN;
    rt_spi_send(spi_flash_device.rt_spi_device, send_buffer, 1);

send_buffer[0] = CMD_ERASE_4K;
    send_buffer[1] = (page >> 16);
    send_buffer[2] = (page >> 8);
    send_buffer[3] = (page);
    rt_spi_send(spi_flash_device.rt_spi_device, send_buffer, 4);

w25qxx_wait_busy(); // wait erase done.

for(index=0; index < (size/256); index++)
    {
        send_buffer[0] = CMD_WREN;
        rt_spi_send(spi_flash_device.rt_spi_device, send_buffer, 1);

send_buffer[0] = CMD_PP;
        send_buffer[1] = (uint8_t)(page >> 16);
        send_buffer[2] = (uint8_t)(page >> 8);
        send_buffer[3] = (uint8_t)(page);

rt_spi_send_then_send(spi_flash_device.rt_spi_device,
                              send_buffer, 4,
                              buffer, 256);

buffer += 256;
        page += 256;
        w25qxx_wait_busy();
    }

send_buffer[0] = CMD_WRDI;
    rt_spi_send(spi_flash_device.rt_spi_device, send_buffer, 1);

return size;
}```
每次进行擦除4kb，在将数据进行写入；

在看看调用它的块设备的写函数：w25qxx_flash_write
```static rt_size_t w25qxx_flash_write(rt_device_t dev,
                                    rt_off_t pos,
                                    const void* buffer,
                                    rt_size_t size)
{
    flash_lock((struct spi_flash_device *)dev);

w25qxx_page_write(pos*spi_flash_device.geometry.bytes_per_sector,
                      buffer,
                      size*spi_flash_device.geometry.bytes_per_sector);

flash_unlock((struct spi_flash_device *)dev);

return size;
}```
这个写函数的最小单位是4kb，就是说是按照4kb的扇区进行写的，这个函数最终会掉用 w25qxx_page_write函数，这个函数在只写一个扇区的时候是没问题的，可是我要写多个扇区的时候就会出现问题了，w25qxx_page_write只擦除了4kb，那我要写超过4kb的数据，比如说写两个扇区的数据，就会出现后面的4kb没有被擦除，导致数据不能被写入flash芯片中，我实际测试过，确实是这样的，我觉的应该是结合实际传入的page地址和具体的扇区个数，将要写的扇区进行统一的擦除，但是很奇怪，realtouch确实正常使用了，也成功挂载了elm-fat，我想问一下是不是故意这样做的，是我的理解有错误，还是这真的是一个bug？