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

Roger Quadros
2017-11-15T10:08:49Z

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).

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.

>
> 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;
}

> 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.

> }
>
> 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");
>
> 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

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