Re: [LINUX PATCH v12 3/3] mtd: rawnand: arasan: Add support for Arasan NAND Flash Controller

Martin Lund
2018-11-12T11:12:15Z

Hi Naga,

Just a few review comments for the v12 version.

On Fri, Nov 9, 2018 at 6:00 AM Naga Sureshkumar Relli
<naga.sureshkumar.relli@xilinx.com> wrote:
> +#define PKT_OFST 0x00
> +#define PKT_CNT_SHIFT 12
> +
> +#define MEM_ADDR1_OFST 0x04
> +#define MEM_ADDR2_OFST 0x08

For the sake of readability I think *_OFFSET is preferred, especially
since the driver already includes short macro names. I think this is
similar to the EVNT vs EVENT point.
The majority of drivers in the Linux kernel do not shorten OFFSET -> OFST.

> +static void anfc_rw_pio_op(struct mtd_info *mtd, u8 *buf, int len,
> + bool do_read, int prog, int pktcount, int pktsize)
> +{
> + struct nand_chip *chip = mtd_to_nand(mtd);
> + struct anfc_nand_controller *nfc = to_anfc(chip->controller);
> + struct anfc_nand_chip *achip = to_anfc_nand(chip);
> + u32 *bufptr = (u32 *)buf;
> + u32 cnt = 0, intr = 0;
> +
> + anfc_config_dma(nfc, 0);
> +
> + if (pktsize == 0)
> + pktsize = len;
> +
> + anfc_setpktszcnt(nfc, pktsize, pktcount);
> +
> + if (!achip->strength)
> + intr = MBIT_ERROR;
> +
> + if (do_read)
> + intr |= READ_READY;
> + else
> + intr |= WRITE_READY;
> + anfc_enable_intrs(nfc, intr);
> + writel(prog, nfc->base + PROG_OFST);
> + while (cnt < pktcount) {
> + anfc_wait_for_event(nfc);
> + cnt++;
> + if (cnt == pktcount)
> + anfc_enable_intrs(nfc, XFER_COMPLETE);
> + if (do_read)
> + ioread32_rep(nfc->base + DATA_PORT_OFST, bufptr,
> + pktsize / 4);
> + else
> + iowrite32_rep(nfc->base + DATA_PORT_OFST, bufptr,
> + pktsize / 4);
> + bufptr += (pktsize / 4);
> + if (cnt < pktcount)
> + anfc_enable_intrs(nfc, intr);
> + }
> + anfc_wait_for_event(nfc);
> +}

Throughout the driver all calls to anfc_wait_for_event() ignores the
timeout return value. It would be nice to see some error handling in
case it times out - at minimum consider printing out an error message
since timeout on NAND operations are fairly critical and should
generally not occur. Perhaps even an argument can be made for
returning -ETIMEDOUT in case of timeout.

I'm putting a focus on this because I see the original non-upstream
Arasan driver sometimes timeout on NAND operations when I stress test
it via the UBI stress test. Not sure what the cause for the timeout is
yet but either way an error message would have been helpful.

Br, Martin