| Message ID | 1560240715-22595-2-git-send-email-qii.wang@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add support for AC timing adjustment | expand |
Hi, On Tue, Jun 11, 2019 at 04:11:54PM +0800, Qii Wang wrote: > Add i2c AC timing binding to binding file. It can give the AC > timing parameters to meet I2C specification at different speed. > > Signed-off-by: Qii Wang <qii.wang@mediatek.com> I think this is a too specific 1:1 mapping of your register set into DT world. We already have these generic parameters: - clock-frequency frequency of bus clock in Hz. - i2c-scl-falling-time-ns Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C specification. - i2c-scl-internal-delay-ns Number of nanoseconds the IP core additionally needs to setup SCL. - i2c-scl-rising-time-ns Number of nanoseconds the SCL signal takes to rise; t(r) in the I2C specification. - i2c-sda-falling-time-ns Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C specification. (check Documentation/devicetree/bindings/i2c/i2c.txt) Can't you use those to derive your values from that? Which ones are you missing if not? Regards, Wolfram
On Wed, 2019-06-26 at 15:39 +0200, Wolfram Sang wrote: > Hi, > > On Tue, Jun 11, 2019 at 04:11:54PM +0800, Qii Wang wrote: > > Add i2c AC timing binding to binding file. It can give the AC > > timing parameters to meet I2C specification at different speed. > > > > Signed-off-by: Qii Wang <qii.wang@mediatek.com> > > I think this is a too specific 1:1 mapping of your register set into DT > world. We already have these generic parameters: > > - clock-frequency > frequency of bus clock in Hz. > > - i2c-scl-falling-time-ns > Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C > specification. > > - i2c-scl-internal-delay-ns > Number of nanoseconds the IP core additionally needs to setup SCL. > > - i2c-scl-rising-time-ns > Number of nanoseconds the SCL signal takes to rise; t(r) in the I2C > specification. > > - i2c-sda-falling-time-ns > Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C > specification. > > (check Documentation/devicetree/bindings/i2c/i2c.txt) > > Can't you use those to derive your values from that? Which ones are you missing > if not? > > Regards, > > Wolfram I have take a little time to develop a new patch which based on your suggestions, and it tested OK. Thanks for your suggestions, I will update the patch after I test it fully.
> > Can't you use those to derive your values from that? Which ones are you missing > > if not? > > I have take a little time to develop a new patch which based on your > suggestions, and it tested OK. Thanks for your suggestions, I will > update the patch after I test it fully. Great news, thanks!
diff --git a/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt b/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt index 68f6d73..0f92813 100644 --- a/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt +++ b/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt @@ -30,6 +30,7 @@ Optional properties: - mediatek,have-pmic: platform can control i2c form special pmic side. Only mt6589 and mt8135 support this feature. - mediatek,use-push-pull: IO config use push-pull mode. + - ac-timing: give some AC timing parameters to meet i2c spec fully. Example: @@ -43,5 +44,15 @@ Example: clock-div = <16>; clocks = <&i2c0_ck>, <&ap_dma_ck>; clock-names = "main", "dma"; + ac-timing = /bits/ 16 < + 0x8001 /* 0:ext */ + 0x0005 /* 1:inter_clk_div */ + 0x0102 /* 2:scl_hl_ratio */ + 0x0102 /* 3:hs_scl_hl_ratio */ + 0x0002 /* 4:scl_mis_comp */ + 0x0002 /* 5:sta_stop */ + 0x0002 /* 6:hs_sta_stop */ + 0x0002 /* 7:sda_timing */ + >; };
Add i2c AC timing binding to binding file. It can give the AC timing parameters to meet I2C specification at different speed. Signed-off-by: Qii Wang <qii.wang@mediatek.com> --- .../devicetree/bindings/i2c/i2c-mt65xx.txt | 11 +++++++++++ 1 file changed, 11 insertions(+)