Hi Linus W,
On 23/05/14 10:31, Linus Walleij wrote:
static int mmci_qcom_pio_read(struct mmci_host *host, char *buffer,
unsigned int remain)
{
u32 *ptr = (u32*) buffer;
unsigned int count = 0;
unsigned int words;
unsigned int fifo_size = host->variant->fifosize;
words = DIV_ROUND_UP(remain, 4);
while (readl(host->base + MMCISTATUS) & MCI_RXDATAAVLBL) {
*ptr = readl(host->base + MMCIFIFO + (count % fifo_size));
ptr++;
count += 4;
remain--;
if (!remain)
break;
}
return count;
}
I guess you will run into additional problems when you come to doing
SDIO. This function can return*more* bytes than asked for, as it rounds
up. It won't happen with MMC/SD transfers since these are always
divisible by 8, but it*will* happen on SDIO!
That's a good point,
Qualcomm will need SDIO support in future, so I have slightly modified
the code to address this. Other thing I tried was to fit in this in
mmci_pio_read, It became very ugly, as the FIFOCNT register behaviour is
totally different and there is no way to tell how many bytes are ready
to be consumed. So finally I think having a separate pio read for
qualcomm looks much neater.
final mmci_qcom_pio_read looks like:
static int mmci_qcom_pio_read(struct mmci_host *host, char *buffer,
unsigned int remain)
{
u32 *ptr = (u32*) buffer;
unsigned int count = 0;
unsigned int words, bytes;
unsigned int fifo_size = host->variant->fifosize;
words = remain >> 2;
bytes = remain % 4;
/* read full words followed by leftover bytes */
if (words) {
while (readl(host->base + MMCISTATUS) & MCI_RXDATAAVLBL) {
*ptr = readl(host->base + MMCIFIFO + (count % fifo_size));
ptr++;
count += 4;
words--;
if (!words)
break;
}
}
/* read leftover bytes */
if (unlikely(bytes)) {
unsigned char buf[4];
if (readl(host->base + MMCISTATUS) & MCI_RXDATAAVLBL) {
*buf = readl(host->base + MMCIFIFO + (count % fifo_size));
memcpy(ptr, buf, bytes);
count += bytes;
}
}
return count;
}
Thanks,
srini
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