Messages in this thread | | | Date | Wed, 30 Oct 2019 11:48:11 +0530 | From | Balakrishna Godavarthi <> | Subject | Re: [PATCH 2/4] Bluetooth: hci_qca: Don't vote for specific voltage |
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Hi Matthias,
On 2019-10-22 22:45, Matthias Kaehlcke wrote: > On Tue, Oct 22, 2019 at 11:35:43AM +0530, Balakrishna Godavarthi wrote: >> Hi Matthias, Bjorn andresson, >> >> On 2019-10-21 12:07, Harish Bandi wrote: >> > + Bala >> > >> > On 2019-10-18 23:52, Matthias Kaehlcke wrote: >> > > On Thu, Oct 17, 2019 at 10:24:02PM -0700, Bjorn Andersson wrote: >> > > > Devices with specific voltage requirements should not request voltage >> > > > from the driver, but instead rely on the system configuration to >> > > > define >> > > > appropriate voltages for each rail. >> > > > >> > > > This ensures that PMIC and board variations are accounted for, >> > > > something >> > > > that the 0.1V range in the hci_qca driver currently tries to address. >> > > > But on the Lenovo Yoga C630 (with wcn3990) vddch0 is 3.1V, which >> > > > means >> > > > the driver will fail to set the voltage. >> > > > >> > > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> >> > > > --- >> > > > drivers/bluetooth/hci_qca.c | 26 ++++++++------------------ >> > > > 1 file changed, 8 insertions(+), 18 deletions(-) >> > > > >> > > > diff --git a/drivers/bluetooth/hci_qca.c >> > > > b/drivers/bluetooth/hci_qca.c >> > > > index c07c529b0d81..54aafcc69d06 100644 >> > > > --- a/drivers/bluetooth/hci_qca.c >> > > > +++ b/drivers/bluetooth/hci_qca.c >> > > > @@ -130,8 +130,6 @@ enum qca_speed_type { >> > > > */ >> > > > struct qca_vreg { >> > > > const char *name; >> > > > - unsigned int min_uV; >> > > > - unsigned int max_uV; >> > > > unsigned int load_uA; >> > > > }; >> > > > >> > > > @@ -1332,10 +1330,10 @@ static const struct hci_uart_proto >> > > > qca_proto = { >> > > > static const struct qca_vreg_data qca_soc_data_wcn3990 = { >> > > > .soc_type = QCA_WCN3990, >> > > > .vregs = (struct qca_vreg []) { >> > > > - { "vddio", 1800000, 1900000, 15000 }, >> > > > - { "vddxo", 1800000, 1900000, 80000 }, >> > > > - { "vddrf", 1300000, 1350000, 300000 }, >> > > > - { "vddch0", 3300000, 3400000, 450000 }, >> > > > + { "vddio", 15000 }, >> > > > + { "vddxo", 80000 }, >> > > > + { "vddrf", 300000 }, >> > > > + { "vddch0", 450000 }, >> > > > }, >> > > > .num_vregs = 4, >> > > > }; >> > > > @@ -1343,10 +1341,10 @@ static const struct qca_vreg_data >> > > > qca_soc_data_wcn3990 = { >> > > > static const struct qca_vreg_data qca_soc_data_wcn3998 = { >> > > > .soc_type = QCA_WCN3998, >> > > > .vregs = (struct qca_vreg []) { >> > > > - { "vddio", 1800000, 1900000, 10000 }, >> > > > - { "vddxo", 1800000, 1900000, 80000 }, >> > > > - { "vddrf", 1300000, 1352000, 300000 }, >> > > > - { "vddch0", 3300000, 3300000, 450000 }, >> > > > + { "vddio", 10000 }, >> > > > + { "vddxo", 80000 }, >> > > > + { "vddrf", 300000 }, >> > > > + { "vddch0", 450000 }, >> > > > }, >> > > > .num_vregs = 4, >> > > > }; >> > > > @@ -1386,13 +1384,6 @@ static int qca_power_off(struct hci_dev *hdev) >> > > > static int qca_enable_regulator(struct qca_vreg vregs, >> > > > struct regulator *regulator) >> > > > { >> > > > - int ret; >> > > > - >> > > > - ret = regulator_set_voltage(regulator, vregs.min_uV, >> > > > - vregs.max_uV); >> > > > - if (ret) >> > > > - return ret; >> > > > - >> > > > return regulator_enable(regulator); >> > > > >> > > > } >> > > > @@ -1401,7 +1392,6 @@ static void qca_disable_regulator(struct >> > > > qca_vreg vregs, >> > > > struct regulator *regulator) >> > > > { >> > > > regulator_disable(regulator); >> > > > - regulator_set_voltage(regulator, 0, vregs.max_uV); >> > > > >> > > > } >> > > >> > > This was brought up multiple times during the initial review, but >> > > wasn't addressed. >> > > >> > > Reviewed-by: Matthias Kaehlcke <mka@chromium.org> >> >> >> yes true PMIC dts regulator should do this. >> But we have some real time issues observed. >> >> Issue 1: >> >> In PMIC dts node, ASAIK we have three levels of voltages. >> >> 1. Default voltage. >> 2. Minimum voltage. (mandatory entry) >> 3. Maximum voltage. (mandatory entry) >> >> Let us assume that the if PMIC regulator dts node supports defaults >> voltage >> to 3.2 Volts and Min as 3.1 V and max as 3.3V >> So default operating voltage is 3.1V when we turn on BT (but >> according to >> spec SoC requires min of 3.3V to operate, >> Might have some functionality failures on end to end testing > > The PMIC regulator shouldn't be configured with the entire range of > voltages > it can generate, but with a range of voltages that is suitable for all > its > consumers. > > In other words if BT requires a minimum voltage of 3.3V the minimum > voltage > of the regulator should be at least 3.3V. > >> Issue 2: >> >> WCN3990 RF is shared with WiFi, so it also try to turn on the >> regulators. >> Wifi driver uses the same approach of restricting to min and max >> voltages in >> driver. >> Let us assume we turned ON BT and CH0 is set to 3.1v (as in your >> case), Wifi >> is tuned on now, as its request the CH0 to operate at 3.3 Volts, >> regulator >> will fail to set this voltage as BT is operating >> at CH0 3.1v (assuming max voltage is 3.2v) >> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/tree/drivers/net/wireless/ath/ath10k/snoc.c#n39 > > see above > >> Issue 3: >> >> By mistake PMIC has low min or default voltage and high max voltages, >> that >> is harm for WNC3990. >> >> I would suggest to restrict the min and max voltages in driver, >> instead of >> relaying on PMIC to do this. >> BTW pmic will do this and doing it in our driver is safer. > > What if another device switches the regulator on before BT? > > Again, what you describe is a misconfiguration of the regulator and > should > be fixed at its root, instead of implementing unreliable 'safeguards' > in each > and every driver using regulators.
Thanks for detail analysis :) -- Regards Balakrishna.
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