Hi Dmitry, Rob,
Thanks for the review.
On Mon, Jan 10, 2022 at 05:06:03PM +0300, Dmitry Baryshkov wrote:
On Mon, 10 Jan 2022 at 15:56, Rajeev Nandan
quic_rajeevny@quicinc.com wrote:
In most cases, the default values of DSI PHY tuning registers should be sufficient as they are fully optimized. However, in some cases where extreme board parasitics cause the eye shape to degrade, the override bits can be used to improve the signal quality.
The general guidelines for DSI PHY tuning include:
- High and moderate data rates may benefit from the drive strength and drive level tuning.
- Drive strength tuning will affect the output impedance and may be used for matching optimization.
- Drive level tuning will affect the output levels without affecting the impedance.
The clock and data lanes have a calibration circuitry feature. The drive strength tuning can be done by adjusting rescode offset for hstop/hsbot, and the drive level tuning can be done by adjusting the LDO output level for the HSTX drive.
Signed-off-by: Rajeev Nandan quic_rajeevny@quicinc.com
Changes in v2:
- More details in the commit text (Stephen Boyd)
- Use human understandable values (Stephen Boyd, Dmitry Baryshkov)
- Do not take values that are going to be unused (Dmitry Baryshkov)
.../bindings/display/msm/dsi-phy-10nm.yaml | 33
++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/Documentation/devicetree/bindings/display/msm/dsi-phy-10nm.yaml b/Documentation/devicetree/bindings/display/msm/dsi-phy-10nm.yaml index 4399715..d0eb8f6 100644
a/Documentation/devicetree/bindings/display/msm/dsi-phy-10nm.yaml +++ b/Documentation/devicetree/bindings/display/msm/dsi-phy-
10nm.yam
+++ l @@ -35,6 +35,35 @@ properties: Connected to DSI0_MIPI_DSI_PLL_VDDA0P9 pin for sc7180 target and connected to VDDA_MIPI_DSI_0_PLL_0P9 pin for sdm845 target
Generic note: I think these properties should be prefixed with "qcom," prefix.
Sure, I will update in next version along with removing encoding for phy-drive-ldo-level property.
- phy-rescode-offset-top:
- $ref: /schemas/types.yaml#/definitions/uint8-array
- minItems: 5
- maxItems: 5
- description:
Integer array of offset for pull-up legs rescode for all five lanes.To offset the drive strength from the calibrated value in an increasingor decreasing manner, use 6 bit two’s complement values.dtc should support negative values, google hints that <(-2)> should work.
This format is working.
Yes, but the schema checks don't check negative values correctly yet. So you can use 'int8-array', but just don't use negative values in the examples. I'm working on changes that will fix this issue.
What does 6-bit mean? 0x3f is negative? Just sign extend the values and specify the valid range instead:
minimum: -32 maximum: 31
Yes, Rob. 0x3f is negative value (-1) in 6-bit two's complement. I will implement your suggestion in the next patch version.
Rob
Thanks, Rajeev