Re: [PATCH v3 4/6] mtd: rawnand: add NVIDIA Tegra NAND Flash controller driver

[Stefan Agner]

On 09.06.2018 07:52, Boris Brezillon wrote:
> On Fri, 08 Jun 2018 23:51:01 +0200
> Stefan Agner <stefan@xxxxxxxx> wrote:
> 
> 
>> >
>> > void tegra_nand_controller_reset(struct tegra_nand_controller *ctrl)
>> > {
>> > 	int err;
>> >
>> > 	disable_irq(ctrl->irq);
>> >
>> > 	err = reset_control_reset(ctrl->rst);
>> > 	if (err) {
>> > 		dev_err(ctrl->dev, "Failed to reset HW: %d\n", err);
>> > 		msleep(HW_TIMEOUT);
>> > 	}
>> >
>> > 	writel_relaxed(NAND_CMD_STATUS, ctrl->regs + HWSTATUS_CMD);
>> > 	writel_relaxed(HWSTATUS_MASK, ctrl->regs + HWSTATUS_MASK);
>> > 	writel_relaxed(INT_MASK, ctrl->regs + ISR);
>>
>> If we do a controller reset, there is much more state than that which
>> needs to be restored. A lot of it is not readily available currently
>> (timing, ECC settings...)
> 
> This is actually a good test to detect what is not properly initialized
> by the driver. Timings should be configured correctly through
> ->setup_data_interface(). ECC engine should be disabled by default and
> only enabled when ->{read,write}_page() is called.
> 

Is setup_data_interface guaranteed to be called after a failed
->exec_op()/{read,write}_page()?

>>
>> That seems a lot of work for a code path I do not intend to ever use :-)
>>
> 
> Not so sure it's a lot of work. If ECC and timing settings are the
> only thing you need to initialize then it should work just fine.
> Try with a controller reset and you'll know if you miss something ;-).

Currently the setting gets written directly to the registers. Only the
enable flag is set in the HW ECC {read,write}_page() functions. So I
will have to store the complete register in the chip structure and write
them on every {read,write}_page()?

--
Stefan