On 23/04/2021 21:24, Bryan O'Donoghue wrote:
On 23/04/2021 17:32, Mark Brown wrote:
On Fri, Apr 23, 2021 at 05:06:58PM +0100, Bryan O'Donoghue wrote:
+ /* Set OTG current limit to 3000mA up from bootloader set 2000mA */
+ regmap_update_bits(regmap, base + OTG_CURRENT_LIMIT_CFG,
+ OTG_CURRENT_LIMIT_MASK, OTG_CURRENT_LIMIT_3000MA);
This seems like something that needs to be configured per system, the
system may not be physically capable of delivering an additional amp
(150% of the current defaults) safely. It's going to be better to be
out of spec for high current USB devices than to exceed safe physical
limits, there's a good solid reason why the regulator API never touches
the hardware without explicit constraints allowing it to do so.
You're right that its per system.
- smb5_pmi632_params.otg_cl.max_u == 1000000
- smb5_pm8150b_params.otg_cl.max_u == 3000000
https://github.com/BeastRoms-Devices/kernel_realme_RMX1927/blame/master/drivers/power/supply/qcom/qpnp-smb5.c
See page 3 here
https://www.st.com/content/ccc/resource/sales_and_marketing/presentation/product_presentation/group0/5a/b1/8e/6c/2b/0d/46/3c/Apec/files/APEC_2016_USB_Power.pdf/_jcr_content/translations/en.APEC_2016_USB_Power.pdf
and section 1.2.2 here
https://cdn.sparkfun.com/assets/e/b/4/f/7/USB-C_Datasheet.pdf
For type-c 3 Amps at 5 Volts is correct or 1.5 Amps at 5 Volts, either
way the default coming out of the bootloader at 2 Amps is wrong.
I also thought there was support in the USB specs for negotiating how
much power is drawn (not that everything will DTRT there but still)?
Right the Power-delivery stuff up to 100 watts is associated with Vconn
which is driven on CC1 or CC2 depending on the orientation of the cable.
https://www.allaboutcircuits.com/uploads/articles/Fig1m11292018.png
This patch deals with the higher spec VBUS current that the pm8150b can
drive, not the power-delivery protocol juice over VCONN.
---
bod
Oh and I should mention the pm8150b is a type-c controller and battery
charger block, so you wouldn't connect it to a USB 3.x type-a port.
The Qualcomm reference schematics drive VBUS for those ports from a
current limiter - a SY6288F1ABC - which steps down 5v/4amp rail to
5v/1.2amp.
So the pm8150b is exclusively for the type-c not type-a ports.
---
bod
