[PATCH v3 5/5] mtd: spi-nor: cadence-quadspi: Add runtime PM support
From: matthew.gerlach at linux.intel.com <hidden>
Date: 2017-09-28 15:01:44
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linux-devicetree, lkml
Hi Vignesh, I tried this patch on an Arria10 SOCFPGA devkit against the 4.1.33-ltsi kernel, and it did not go well. Commands to the flash chip timedout resulting in the probe function failing. I ran into other problems, not related to cadence-quadspi, that prevented me from testing against 4.9 and 4.12 kernels, but I suspect similar behavior. Matthew Gerlach On Wed, 27 Sep 2017, Vignesh R wrote:
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Hi Matthew, On Tuesday 26 September 2017 05:19 AM, Marek Vasut wrote: [...]quoted
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Ok thanks! Do you know if pm_runtime_get_sync() can enable clocks for QSPI on SoCFPGA or if clk_prepare_enable() is needed? Just trying to see if its possible to get rid of clk_*() calls in favor of pm_*() calls.Not of the top of my head, sorry. +CC Matthew, he should know.I am not an expert at the clock framework nor the power management, but I did ask around a bit.? No one I asked was planning to change the clk_*() calls to pm_*() call, but the feedback was that it would be a good idea.The question is, if we do the replacement, will it break on socfpga ? A quick test might be useful.yes, a quick qspi test with clk_prepare_enable() replaced by pm_*() calls like below patch would be helpful:diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c index 53c7d8e0327a..7ad3e176cc88 100644 --- a/drivers/mtd/spi-nor/cadence-quadspi.c +++ b/drivers/mtd/spi-nor/cadence-quadspi.c@@ -34,6 +34,7 @@#include <linux/sched.h> #include <linux/spi/spi.h> #include <linux/timer.h> +#include <linux/pm_runtime.h> #define CQSPI_NAME "cadence-qspi" #define CQSPI_MAX_CHIPSELECT 16@@ -1206,11 +1207,8 @@ static int cqspi_probe(struct platform_device *pdev) return -ENXIO; } - ret = clk_prepare_enable(cqspi->clk); - if (ret) { - dev_err(dev, "Cannot enable QSPI clock.\n"); - return ret; - } + pm_runtime_enable(dev); + pm_runtime_get_sync(dev); cqspi->master_ref_clk_hz = clk_get_rate(cqspi->clk);-- Regards Vignesh