On Tue, Apr 29, 2014 at 10:21 AM, <srinivas.kandagatla@xxxxxxxxxx> wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
>
> MCIFIFOCNT register behaviour on Qcom chips is very different than the other
> pl180 integrations. MCIFIFOCNT register contains the number of
> words that are still waiting to be transferred through the FIFO. It keeps
> decrementing once the host CPU reads the MCIFIFO. With the existing logic and
> the MCIFIFOCNT behaviour, mmci_pio_read will loop forever, as the FIFOCNT
> register will always return transfer size before reading the FIFO.
>
> Also the data sheet states that "This register is only useful for debug
> purposes and should not be used for normal operation since it does not reflect
> data which may or may not be in the pipeline".
>
> This patch implements qcom_pio_read function so as existing mmci_pio_read is
> not suitable for Qcom SOCs.
>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
(...)
> +static int mmci_qcom_pio_read(struct mmci_host *host, char *buffer,
> + unsigned int remain)
> +{
> + uint32_t *ptr = (uint32_t *) buffer;
Just use u32 for this.
> + int count = 0;
> + struct variant_data *variant = host->variant;
> + int fifo_size = variant->fifosize;
> +
> + if (remain % 4)
> + remain = ((remain >> 2) + 1) << 2;
Explain in a comment exactly what is happening here or noone will
understand the code.
> + while (readl(host->base + MMCISTATUS) & MCI_RXDATAAVLBL) {
> + *ptr = readl(host->base + MMCIFIFO + (count % fifo_size));
> + ptr++;
> + count += sizeof(uint32_t);
> + remain -= sizeof(uint32_t);
sizeof(u32) or just 4 works for these...
count += 4;
remain -= 4;
Is easier to parse and understand I think.
> + if (remain == 0)
> + break;
if (!remain)
break;
> + }
> + return count;
> +}
> - if (status & MCI_RXACTIVE)
> - len = mmci_pio_read(host, buffer, remain);
> + if (status & MCI_RXACTIVE) {
> + if (host->hw_designer == AMBA_VENDOR_QCOM)
> + len = mmci_qcom_pio_read(host, buffer, remain);
> + else
> + len = mmci_pio_read(host, buffer, remain);
> + }
Use something like bool qcom_fifo; in vendor data instead.
Yours,
Linus Walleij
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