From: <Tudor.Ambarus@microchip.com>
To: <dinguyen@kernel.org>, <linux-mtd@lists.infradead.org>
Cc: <marex@denx.de>, <dwmw2@infradead.org>,
<computersforpeace@gmail.com>, <bbrezillon@kernel.org>,
<vigneshr@ti.com>, <linux-kernel@vger.kernel.org>,
<tien.fong.chee@intel.com>
Subject: Re: [PATCHv2] mtd: spi-nor: cadence-quadspi: add reset control
Date: Wed, 17 Apr 2019 08:48:45 +0000 [thread overview]
Message-ID: <5e058af4-17d8-9db9-5bc5-2122d3af4c9f@microchip.com> (raw)
In-Reply-To: <20190409153801.6941-1-dinguyen@kernel.org>
Hi, Dinh,
On 04/09/2019 06:38 PM, Dinh Nguyen wrote:
> Get the reset control for the QSPI controller and bring it out of reset.
Is there a public datasheet where I can check this?
>
> Suggested-by: Tien-Fong Chee <tien.fong.chee@intel.com>
> Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
> ---
> v2: use devm_reset_control_get_optional_exclusive
> print an error message
> return -EPROBE_DEFER
> ---
> drivers/mtd/spi-nor/cadence-quadspi.c | 14 ++++++++++++++
would you update the bindings as well?
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
> index 792628750eec..c548567adcf0 100644
> --- a/drivers/mtd/spi-nor/cadence-quadspi.c
> +++ b/drivers/mtd/spi-nor/cadence-quadspi.c
> @@ -34,6 +34,7 @@
> #include <linux/of.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> +#include <linux/reset.h>
> #include <linux/sched.h>
> #include <linux/spi/spi.h>
> #include <linux/timer.h>
> @@ -1336,6 +1337,7 @@ static int cqspi_probe(struct platform_device *pdev)
> struct cqspi_st *cqspi;
> struct resource *res;
> struct resource *res_ahb;
> + struct reset_control *rstc;
> const struct cqspi_driver_platdata *ddata;
> int ret;
> int irq;
> @@ -1362,6 +1364,18 @@ static int cqspi_probe(struct platform_device *pdev)
> return PTR_ERR(cqspi->clk);
> }
>
> + /* Obtain QSPI reset control */
OSPI version of the IP has been added recently. Is this available just for QSPI?
> + rstc = devm_reset_control_get_optional_exclusive(dev, NULL);
> + if (IS_ERR(rstc)) {
> + dev_err(dev, "Cannot get QSPI reset.\n");
> + if (PTR_ERR(rstc) == -EPROBE_DEFER)
> + return -EPROBE_DEFER;
why ignoring all the other possible errors? Maybe return PTR_ERR(rstc); ?
> + } else {
> + reset_control_assert(rstc);
Shouldn't the clock be enabled before asserting reset?
Does it matter if reset_control_assert() is returning any error?
> + udelay(1);
Is there a range or 1 us is the maximum time that we should wait?
> + reset_control_deassert(rstc);
Should we check if reset_control_deassert() is returning any error?
Cheers,
ta
> + }
> +
> /* Obtain and remap controller address. */
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> cqspi->iobase = devm_ioremap_resource(dev, res);
>
next prev parent reply other threads:[~2019-04-17 8:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-09 15:38 [PATCHv2] mtd: spi-nor: cadence-quadspi: add reset control Dinh Nguyen
2019-04-17 8:48 ` Tudor.Ambarus [this message]
2019-05-07 19:17 ` Dinh Nguyen
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