From: Xiaofei Tan <tanxiaofei@huawei.com>
Date: Wed, 7 Mar 2018 20:25:05 +0800
Subject: scsi: hisi_sas: dt-bindings: add an property of signal attenuation
Git-commit: 4c40db995eb54c3ee8cb5a8340640f49395d5f9e
Patch-mainline: v4.17-rc1
References: FATE#326253
For some new boards with hip07 chipset we are required to set PHY config
registers differently. The hw property which determines how to set these
registers is in the PHY signal attenuation readings.
This patch add an devicetree property, "hisilicon,signal-attenuation", which
is used to describe the signal attenuation of an board.
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
Documentation/devicetree/bindings/scsi/hisilicon-sas.txt | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/Documentation/devicetree/bindings/scsi/hisilicon-sas.txt b/Documentation/devicetree/bindings/scsi/hisilicon-sas.txt
index df3bef7998fa..8c6659ed2cfc 100644
--- a/Documentation/devicetree/bindings/scsi/hisilicon-sas.txt
+++ b/Documentation/devicetree/bindings/scsi/hisilicon-sas.txt
@@ -53,6 +53,13 @@ Main node required properties:
Optional main node properties:
- hip06-sas-v2-quirk-amt : when set, indicates that the v2 controller has the
"am-max-transmissions" limitation.
+ - hisilicon,signal-attenuation : array of 3 32-bit values, containing de-emphasis,
+ preshoot, and boost attenuation readings for the board. They
+ are used to describe the signal attenuation of the board. These
+ values' range is 7600 to 12400, and used to represent -24dB to
+ 24dB.
+ The formula is "y = (x-10000)/10000". For example, 10478
+ means 4.78dB.
Example:
sas0: sas@c1000000 {