Re: [PATCH v4 12/16] mtd: onenand: omap2: Enable DMA by default

Roger Quadros
2017-11-15T10:44:02Z

On 15/11/17 12:32, Ladislav Michl wrote:
> On Wed, Nov 15, 2017 at 12:08:05PM +0200, Roger Quadros wrote:
>> Hi,
>>
>> On 11/11/17 23:24, Ladislav Michl wrote:
>>> DMA and R/B pin are independent on each other. Use DMA by default.
>>
>> Is there a R/B pin on Onenand? It looks more like it has a RDY pin and
>> an INT pin (which is used for command completion interrupt).
>
> (See also my previous answer) Yes, there's RDY and INT pin. I tried to use
> the same scheme as NAND is using, but perhaps it doesn't fit too well here.
> Therefore I'm proposing to keep INT pin name and use int-gpios in DT
> bindings. Suggestions?
>
>> I think the subject and message are a bit misleading.
>>
>> It should be something like
>>
>> mtd: onenand: omap2: decouple DMA enabling from INT pin availability
>>
>> INT pin (gpio_irq) is not really needed for DMA but only for notification
>> when a command that needs wait has completed. We can still have DMA
>> even without gpio_irq available.
>
> Thanks, that's definitely better :-)
>
>>> Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
>>> ---
>>> Changes:
>>> -v4: new patch
>>>
>>> drivers/mtd/onenand/omap2.c | 41 +++++++++++++++++------------------------
>>> 1 file changed, 17 insertions(+), 24 deletions(-)
>>>
>>> diff --git a/drivers/mtd/onenand/omap2.c b/drivers/mtd/onenand/omap2.c
>>> index e4857a41760d..62e4ede918c4 100644
>>> --- a/drivers/mtd/onenand/omap2.c
>>> +++ b/drivers/mtd/onenand/omap2.c
>>> @@ -152,17 +152,13 @@ static int omap2_onenand_wait(struct mtd_info *mtd, int state)
>>> }
>>>
>>> reinit_completion(&c->irq_done);
>>> - if (c->gpio_irq) {
>>> - result = gpio_get_value(c->gpio_irq);
>>> - if (result == -1) {
>>> - ctrl = read_reg(c, ONENAND_REG_CTRL_STATUS);
>>> - intr = read_reg(c, ONENAND_REG_INTERRUPT);
>>> - wait_err("gpio error", state, ctrl, intr);
>>> - return -EIO;
>>> - }
>>> - } else
>>> - result = 0;
>>> - if (result == 0) {
>>> + result = gpio_get_value(c->gpio_irq);
>>> + if (result < 0) {
>>> + ctrl = read_reg(c, ONENAND_REG_CTRL_STATUS);
>>> + intr = read_reg(c, ONENAND_REG_INTERRUPT);
>>> + wait_err("gpio error", state, ctrl, intr);
>>> + return -EIO;
>>> + } else if (result == 0) {
>>> int retry_cnt = 0;
>>> retry:
>>> if (!wait_for_completion_io_timeout(&c->irq_done,
>>> @@ -513,13 +509,15 @@ static int omap2_onenand_probe(struct platform_device *pdev)
>>
>> We need to get rid if this code from probe.
>>
>> if (pdata->dma_channel < 0) {
>> /* if -1, don't use DMA */
>> c->gpio_irq = 0;
>> }
>
> Yes. I overlooked it when shuffling with patches. In ended in later patch, but it
> really belongs here. Will fix.
>
>>> dev_err(&pdev->dev, "Failed to request GPIO%d for "
>>> "OneNAND\n", c->gpio_irq);
>>> goto err_iounmap;
>>> - }
>>> - gpio_direction_input(c->gpio_irq);
>>> + }
>>> + gpio_direction_input(c->gpio_irq);
>>> +
>>> + if ((r = request_irq(gpio_to_irq(c->gpio_irq),
>>> + omap2_onenand_interrupt, IRQF_TRIGGER_RISING,
>>> + pdev->dev.driver->name, c)) < 0)
>>> + goto err_release_gpio;
>>>
>>> - if ((r = request_irq(gpio_to_irq(c->gpio_irq),
>>> - omap2_onenand_interrupt, IRQF_TRIGGER_RISING,
>>> - pdev->dev.driver->name, c)) < 0)
>>> - goto err_release_gpio;
>>> + this->wait = omap2_onenand_wait;
>>> }
>>>
>>> if (pdata->dma_channel >= 0) {
>>> @@ -529,15 +527,11 @@ static int omap2_onenand_probe(struct platform_device *pdev)
>>> dma_cap_set(DMA_MEMCPY, mask);
>>>
>>> c->dma_chan = dma_request_channel(mask, NULL, NULL);
>>> - if (!c->dma_chan)
>>> - dev_info(&pdev->dev,
>>> - "failed to allocate DMA for OneNAND, "
>>> - "using PIO instead\n");
>>
>> Why get rid of the print message? Instead we could choose to error out completely
>> if a DMA channel was provided and we couldn't get it.
>
> The point is that without pdata->dma_channel condition above, DMA is always
> enabled and it seems too strict to me to fail, when driver can continue to work.

OK. fair enough.

>
>>> }
>>>
>>> dev_info(&pdev->dev, "initializing on CS%d, phys base 0x%08lx, virtual "
>>> - "base %p, freq %d MHz\n", c->gpmc_cs, c->phys_base,
>>> - c->onenand.base, c->freq);
>>> + "base %p, freq %d MHz, %s mode\n", c->gpmc_cs, c->phys_base,
>>> + c->onenand.base, c->freq, c->dma_chan ? "DMA" : "PIO");
>
> See here ^. We just merely print message driver is running in PIO mode.
>
>>> c->pdev = pdev;
>>> c->mtd.priv = &c->onenand;
>>> @@ -547,7 +541,6 @@ static int omap2_onenand_probe(struct platform_device *pdev)
>>>
>>> this = &c->onenand;
>>> if (c->dma_chan) {
>>> - this->wait = omap2_onenand_wait;
>>> this->read_bufferram = omap2_onenand_read_bufferram;
>>> this->write_bufferram = omap2_onenand_write_bufferram;
>>> }
>>>
>>
>> --
>> cheers,
>> -roger
>>
>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

--
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki