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

[Roger Quadros]

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 at 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