| Message ID | 20241003111525.779410-2-michael.wu@kneron.us |
|---|---|
| State | New |
| Headers | show |
| Series | Compute HS HCNT and LCNT based on HW parameters | expand |
On 03/10/2024 13:15, Michael Wu wrote: > Since there are no registers controlling the hardware parameters > IC_CAP_LOADING and IC_CLK_FREQ_OPTIMIZATION, their values can only be > declared in the device tree. > > snps,bus-capacitance-pf indicates the bus capacitance in picofarads (pF). > It affects the high and low pulse width of SCL line in high speed mode. > The legal values for this property are 100 and 400 only, and default > value is 100. This property corresponds to IC_CAP_LOADING. > > snps,clk-freq-optimized indicates whether the hardware reduce its > internal clock frequency by reducing the internal latency required to > generate the high period and low period of SCL line. This property > corresponds to IC_CLK_FREQ_OPTIMIZATION. > > The driver can calculate the high period count and low period count of > SCL line for high speed mode based on these two properties. > > Signed-off-by: Michael Wu <michael.wu@kneron.us> > --- Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> --- <form letter> This is an automated instruction, just in case, because many review tags are being ignored. If you know the process, you can skip it (please do not feel offended by me posting it here - no bad intentions intended). If you do not know the process, here is a short explanation: Please add Acked-by/Reviewed-by/Tested-by tags when posting new versions, under or above your Signed-off-by tag. Tag is "received", when provided in a message replied to you on the mailing list. Tools like b4 can help here. However, there's no need to repost patches *only* to add the tags. The upstream maintainer will do that for tags received on the version they apply. https://elixir.bootlin.com/linux/v6.5-rc3/source/Documentation/process/submitting-patches.rst#L577 </form letter> Best regards, Krzysztof
diff --git a/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml b/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml index 60035a787e5c..e5d05263c45a 100644 --- a/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml +++ b/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml @@ -97,6 +97,22 @@ properties: - const: tx - const: rx + snps,bus-capacitance-pf: + $ref: /schemas/types.yaml#/definitions/uint32 + description: + This property indicates the bus capacitance in picofarads (pF). + This value is used to compute the tHIGH and tLOW periods for high speed + mode. + enum: [100, 400] + default: 100 + + snps,clk-freq-optimized: + description: + This property indicates whether the hardware reduce its clock frequency + by reducing the internal latency required to generate the high period and + low period of SCL line. + type: boolean + unevaluatedProperties: false required: @@ -121,6 +137,8 @@ examples: i2c-sda-hold-time-ns = <300>; i2c-sda-falling-time-ns = <300>; i2c-scl-falling-time-ns = <300>; + snps,bus-capacitance-pf = <400>; + snps,clk-freq-optimized; }; - | i2c@2000 {
Since there are no registers controlling the hardware parameters IC_CAP_LOADING and IC_CLK_FREQ_OPTIMIZATION, their values can only be declared in the device tree. snps,bus-capacitance-pf indicates the bus capacitance in picofarads (pF). It affects the high and low pulse width of SCL line in high speed mode. The legal values for this property are 100 and 400 only, and default value is 100. This property corresponds to IC_CAP_LOADING. snps,clk-freq-optimized indicates whether the hardware reduce its internal clock frequency by reducing the internal latency required to generate the high period and low period of SCL line. This property corresponds to IC_CLK_FREQ_OPTIMIZATION. The driver can calculate the high period count and low period count of SCL line for high speed mode based on these two properties. Signed-off-by: Michael Wu <michael.wu@kneron.us> --- .../bindings/i2c/snps,designware-i2c.yaml | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)