Messages in this thread | | | Subject | Re: [PATCH] i2c: designware: make *CNT values configurable | From | Jarkko Nikula <> | Date | Thu, 26 Oct 2017 17:16:07 +0300 |
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Hi
On 10/25/2017 09:50 PM, Shikhar Dogra wrote: > The values are already configurable from ACPI. > > This patch makes the high count (HCNT) and low count (LCNT) > register values configurable through device tree. > > Cc: xe-linux-external@cisco.com > Signed-off-by: Shikhar Dogra <shidogra@cisco.com> > --- > Documentation/devicetree/bindings/i2c/i2c-designware.txt | 16 ++++++++++++++++ > drivers/i2c/busses/i2c-designware-platdrv.c | 12 ++++++++++++ > 2 files changed, 28 insertions(+) > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > index fee26dc..2b9ddca 100644 > --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt > +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > @@ -20,6 +20,18 @@ Optional properties : > - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds. > This value which is by default 300ns is used to compute the tHIGH period. > > + - i2c-ss-hcnt : should contain the I2C controller standard speed HCNT value. > + If this is not set we use the calculated and more conservative values. > + > + - i2c-ss-lcnt : should contain the I2C controller standard speed LCNT value. > + If this is not set we use the calculated and more conservative values. > + > + - i2c-fs-hcnt : should contain the I2C controller fast speed HCNT value. > + If this is not set we use the calculated and more conservative values. > + > + - i2c-fs-lcnt : should contain the I2C controller fast speed LCNT value. > + If this is not set we use the calculated and more conservative values. > +
Worth to add also properties for high-speed while at it.
Out of curiosity, are calculated values by using "i2c-sda-falling-time-ns" and "i2c-scl-falling-time-ns" properties non-optimal on your platform and controller clock?
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c > index 6b00061c..25c3b0c 100644 > --- a/drivers/i2c/busses/i2c-designware-platdrv.c > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c > @@ -177,6 +177,18 @@ static int dw_i2c_plat_probe(struct platform_device *pdev) > of_property_read_u32(pdev->dev.of_node, "clock-frequency", > &clk_freq); > > + of_property_read_u16(pdev->dev.of_node, > + "i2c-ss-hcnt", &dev->ss_hcnt); > +
This patch is against old kernel. These were converted near 2 years ago by the commit 4c5301abbf81 ("i2c: designware: Convert to use unified device property API")
-- Jarkko
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