Messages in this thread | | | Date | Mon, 11 Apr 2022 09:42:28 +0200 | Subject | Re: [PATCH v2 1/5] drm: bridge: dw_hdmi: cec: Add cec suspend/resume function | From | Neil Armstrong <> |
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On 10/04/2022 12:13, Jernej Škrabec wrote: > Dne petek, 08. april 2022 ob 15:41:36 CEST je Neil Armstrong napisal(a): >> On 08/04/2022 12:32, Sandor Yu wrote: >>> CEC interrupt status/mask and logical address registers >>> will be reset when device enter suspend. >>> It will cause cec fail to work after device resume. >>> Add CEC suspend/resume functions, reinitialize logical address registers >>> and restore interrupt status/mask registers after resume. >>> >>> Signed-off-by: Sandor Yu <Sandor.yu@nxp.com> >>> --- >>> >>> drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c | 37 +++++++++++++++++++ >>> 1 file changed, 37 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c >>> b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c index >>> c8f44bcb298a..ab176401b727 100644 >>> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c >>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c >>> @@ -62,6 +62,10 @@ struct dw_hdmi_cec { >>> >>> bool rx_done; >>> struct cec_notifier *notify; >>> int irq; >>> >>> + >>> + u8 regs_polarity; >>> + u8 regs_mask; >>> + u8 regs_mute_stat0; >>> >>> }; >>> >>> static void dw_hdmi_write(struct dw_hdmi_cec *cec, u8 val, int offset) >>> >>> @@ -306,11 +310,44 @@ static int dw_hdmi_cec_remove(struct platform_device >>> *pdev)> >>> return 0; >>> >>> } >>> >>> +static int __maybe_unused dw_hdmi_cec_resume(struct device *dev) >>> +{ >>> + struct dw_hdmi_cec *cec = dev_get_drvdata(dev); >>> + >>> + /* Restore logical address */ >>> + dw_hdmi_write(cec, cec->addresses & 255, HDMI_CEC_ADDR_L); >>> + dw_hdmi_write(cec, cec->addresses >> 8, HDMI_CEC_ADDR_H); >>> + >>> + /* Restore interrupt status/mask register */ >>> + dw_hdmi_write(cec, cec->regs_polarity, HDMI_CEC_POLARITY); >>> + dw_hdmi_write(cec, cec->regs_mask, HDMI_CEC_MASK); >>> + dw_hdmi_write(cec, cec->regs_mute_stat0, HDMI_IH_MUTE_CEC_STAT0); >>> + >>> + return 0; >>> +} >>> + >>> +static int __maybe_unused dw_hdmi_cec_suspend(struct device *dev) >>> +{ >>> + struct dw_hdmi_cec *cec = dev_get_drvdata(dev); >>> + >>> + /* store interrupt status/mask register */ >>> + cec->regs_polarity = dw_hdmi_read(cec, HDMI_CEC_POLARITY); >>> + cec->regs_mask = dw_hdmi_read(cec, HDMI_CEC_MASK); >>> + cec->regs_mute_stat0 = dw_hdmi_read(cec, HDMI_IH_MUTE_CEC_STAT0); >>> + >>> + return 0; >>> +} >>> + >>> +static const struct dev_pm_ops dw_hdmi_cec_pm = { >>> + SET_SYSTEM_SLEEP_PM_OPS(dw_hdmi_cec_suspend, dw_hdmi_cec_resume) >>> +}; >>> + >>> >>> static struct platform_driver dw_hdmi_cec_driver = { >>> >>> .probe = dw_hdmi_cec_probe, >>> .remove = dw_hdmi_cec_remove, >>> .driver = { >>> >>> .name = "dw-hdmi-cec", >>> >>> + .pm = &dw_hdmi_cec_pm, >>> >>> }, >>> >>> }; >>> module_platform_driver(dw_hdmi_cec_driver); >> >> As Hans said on v1, why don't you call dw_hdmi_cec_enable(cec->adap, false) >> in suspend and dw_hdmi_cec_enable(cec->adap, true) in resume ? >> >> With this, CEC engine is not disabled on suspend. > > This should not be done, at least not unconditionally. CEC wakeup > functionality is used by Crust firmware for Allwinner boards. In fact, DW HDMI > CEC controller was designed with suspend/resume functionality in mind. If > properly set, it can autonomously scan for preset CEC messages and generate > interrupt when found. > > Actually, I'm not fan of this patch, since it looks like workaround for power > management firmware not restoring previous state. Or is this HW issue? In any > case, Allwinner SoCs with DW-HDMI CEC don't need restoring any register, so > it's certainly not a general issue.
In this case I think it should explicit in the hdmi_plat_data to either let CEC enabled on suspend or then disable CEC on suspend.
> >> >> Do you plan to use the engine from the suspend code ? > > As mentioned before, it's already done for Allwinner, so CEC should remain > enabled
Thanks for confirming that
> > Best regards, > Jernej > >> >> Neil > > > >
Neil
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