Re: [PATCH v9 2/3] mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs

From: Harvey Hunt
Date: Tue Dec 08 2015 - 11:36:19 EST




On 08/12/15 16:26, Boris Brezillon wrote:
On Tue, 8 Dec 2015 16:03:55 +0000
Harvey Hunt <harvey.hunt@xxxxxxxxxx> wrote:


static void jz4780_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
unsigned int ctrl)
{
struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
struct jz4780_nand_cs *cs;

if (WARN_ON(nfc->selected < 0))
return;

cs = &nfc->cs[nfc->selected];

if (ctrl & NAND_CTRL_CHANGE) {
if (cmd != NAND_CMD_NONE) {
if (ctrl & NAND_ALE)
writeb(cmd, cs->base + OFFSET_ADDR);
else if (ctrl & NAND_CLE)
writeb(cmd, cs->base + OFFSET_CMD);
}

jz4780_nemc_assert(nfc->dev, cs->bank, ctrl & NAND_NCE);
}
}


Okay, I understand your point now. I would also have to implement the
read/write functions to replace the defaults, correct? If so, it feels
strange to add functions to reimplement the default ones.


Actually it should be something like this, because NAND_CTRL_CHANGE is
cleared after the first address cycle.

static void jz4780_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
unsigned int ctrl)
{
struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
struct jz4780_nand_cs *cs;

if (WARN_ON(nfc->selected < 0))
return;

cs = &nfc->cs[nfc->selected];

jz4780_nemc_assert(nfc->dev, cs->bank, ctrl & NAND_NCE);

if (cmd == NAND_CMD_NONE)
return;

if (ctrl & NAND_ALE)
writeb(cmd, cs->base + OFFSET_ADDR);
else if (ctrl & NAND_CLE)
writeb(cmd, cs->base + OFFSET_CMD);
}


Thanks for the example code, I'll try it out for the next version.
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