On 11/16/2024 4:29 PM, Konrad Dybcio wrote:
On 16.11.2024 2:37 AM, Krishna chaitanya chundru wrote:PCIe equalization presets are predefined settings used to optimize signal integrity by compensating for signal loss and distortion in high-speed data transmission. As per PCIe spec 6.0.1 revision section 8.3.3.3 & 4.2.4 for data rates of 8.0 GT/s, 16.0 GT/s, 32.0 GT/s, and 64.0 GT/s, there is a way to configure lane equalization presets for each lane to enhance the PCIe link reliability. Each preset value represents a different combination of pre-shoot and de-emphasis values. For each data rate, different registers are defined: for 8.0 GT/s, registers are defined in section 7.7.3.4; for 16.0 GT/s, in section 7.7.5.9, etc. The 8.0 GT/s rate has an extra receiver preset hint, requiring 16 bits per lane, while the remaining data rates use 8 bits per lane. Based on the number of lanes and the supported data rate, this function reads the device tree property and stores in the presets structure. Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx> --- drivers/pci/of.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci.h | 17 +++++++++++++-- 2 files changed, 77 insertions(+), 2 deletions(-) diff --git a/drivers/pci/of.c b/drivers/pci/of.c index dacea3fc5128..0d37bc231956 100644 --- a/drivers/pci/of.c +++ b/drivers/pci/of.c @@ -826,3 +826,65 @@ u32 of_pci_get_slot_power_limit(struct device_node *node, return slot_power_limit_mw; } EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit); + +int of_pci_get_equalization_presets(struct device *dev, + struct pci_eq_presets *presets, + int num_lanes) +{ + int ret; + + if (of_property_present(dev->of_node, "eq-presets-8gts")) { + presets->eq_presets_8gts = devm_kzalloc(dev, sizeof(u16) * num_lanes, GFP_KERNEL); + if (!presets->eq_presets_8gts)If you make this an array with enum indices, you can make a for loop and read "eq-presets-%ugts", (8 << i) Konrad
as "eq-presets-8gts" is u16 array and other properties are u8 array. I will use as it is for "eq-presets-8gts", but for remaining properties I will use for loop as suggested by you. - Krishna Chaitanya.
