Re: [RFC PATCH] drivers: ata: Read Rx water mark value from device-tree
From: Arnd Bergmann <arnd@arndb.de>
Date: 2016-02-20 22:35:05
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On Saturday 20 February 2016 18:48:22 Anurag Kumar Vulisha wrote:
quoted hunk ↗ jump to hunk
index 7ca8b97..7e48dfc 100644--- a/Documentation/devicetree/bindings/ata/ahci-ceva.txt +++ b/Documentation/devicetree/bindings/ata/ahci-ceva.txt@@ -8,6 +8,7 @@ Required properties: Optional properties: - ceva,broken-gen2: limit to gen1 speed instead of gen2. + - ceva,rx-watermark: RX fifo water mark level for SATA controller. Examples: ahci@fd0c0000 {@@ -17,4 +18,5 @@ Examples: interrupts = <0 133 4>; clocks = <&clkc SATA_CLK_ID>; ceva,broken-gen2; + ceva,rx-watermark = <0x40>; };
How would a hardware integrator know which value is right for a particular SoC? Could it be keyed off the hardware ID? Could the bootloader perhaps set an appropriate value in the AHCI_VEND_PTC register at boot time and the driver read the initial value from it?
From the description, it sounds like this is a policy decision
rather than hardware description, and shouldn't really be in here. Arnd