Hi Dmitry, On Sun, Jul 27, 2025 at 08:07:37PM +0300, Dmitry Baryshkov wrote: > On Thu, Jul 24, 2025 at 08:50:53PM +0200, Henrik Grimler wrote: > > To use MHL we currently need the MHL chip to be permanently on, which > > consumes unnecessary power. Let's use extcon attached to MUIC to enable > > the MHL chip only if it detects an MHL cable. > > Does HPD GPIO reflect the correct state of the cable?
Yes, the HPD gpio pin changes state from low to high when a mhl cable is connected: $ sudo cat /sys/kernel/debug/gpio|grep gpio-755 gpio-755 ( |hpd ) in lo IRQ $ sudo cat /sys/kernel/debug/gpio|grep gpio-755 gpio-755 ( |hpd ) in hi IRQ so that is described correctly. > What is the order of events in such a case? Order of events as in function tracing log? I enabled function tracing with these filters: 'max77693_muic_*' 'samsung_dsim_*' 'drm_bridge_*' 'drm_atomic_bridge_*' 'exynos_irq_*' 'hdmi*' 'sii9234_*' and captured the calls when I connect cable. dmesg with debug output at the same time gives: [ 6568.462521] max77693-muic max77693-muic: external connector is attached (adc:0x00, prev_adc:0x0) [ 6568.470575] max77693-charger max77693-charger: not charging. connector type: 13 [ 6568.491722] sii9234 15-0039: sii9234: detection started d3 [ 6569.398148] i2c i2c-15: sendbytes: NAK bailout. [ 6569.401477] sii9234 15-0039: writebm: TPI[0x3d] <- 0x3e [ 6569.408403] max77693-muic max77693-muic: external connector is attached (adc:0x00, prev_adc:0x0) [ 6569.422638] max77693-charger max77693-charger: not charging. connector type: 13 [ 6569.570615] sii9234 15-0039: sii9234_irq_thread [ 6569.622846] sii9234 15-0039: irq 00/00 42/5c 00/00 [ 6569.626182] sii9234 15-0039: RGND_READY_INT [ 6570.592367] sii9234 15-0039: sii9234_irq_thread [ 6570.644626] sii9234 15-0039: irq 00/60 40/5c 00/00 [ 6570.656185] sii9234 15-0039: RGND 1K!! [ 6570.937165] sii9234 15-0039: sii9234_irq_thread [ 6570.989467] sii9234 15-0039: irq 20/60 00/5c 00/0c [ 6571.000986] sii9234 15-0039: MHL cable connected.. RSEN High [ 6571.222655] sii9234 15-0039: sii9234_irq_thread [ 6571.274884] sii9234 15-0039: irq 00/60 04/5c 00/04 [ 6571.278219] sii9234 15-0039: mhl est interrupt [ 6571.408117] sii9234 15-0039: sii9234_irq_thread [ 6571.460346] sii9234 15-0039: irq 40/60 00/5c 00/04 and in captured trace I see that on cable connect we get an irq that is handled through: 1. max77693_muic_irq_handler 2. max77693_muic_irq_work 3. max77693_muic_adc_handler 4. sii9234_extcon_notifier 5. sii9234_extcon_work 6. sii9234_cable_in 7. hdmi_irq_thread Raw captured trace dat file can be found here: https://grimler.se/files/sii9234-mhl-connect-trace.dat Maybe you were asking for some other type of order of events log though, please let me know if I misunderstand. > Should the sii9234 signal to Exynos HDMI that the link is established? Maybe.. Sorry, I do not know enough about extcon and drm yet. I assume you mean through drm_helper_hpd_irq_event() and drm_bridge_hpd_notify(), I will experiment a bit and add it to the driver and see if this improves it. There is currently (as I wrote to Marek Szyprowski in a response in v1) an issue where device screen stops working if cable is connected when device screen is off, maybe proper notification would help.. > > Signed-off-by: Henrik Grimler <hen...@grimler.se> > > --- > > v2: add dependency on extcon. Issue reported by kernel test robot > > <l...@intel.com> > > --- > > drivers/gpu/drm/bridge/Kconfig | 1 + > > drivers/gpu/drm/bridge/sii9234.c | 89 > > ++++++++++++++++++++++++++++++++++++++-- > > 2 files changed, 87 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig > > index > > b9e0ca85226a603a24f90c6879d1499f824060cb..f18a083f6e1c6fe40bde5e65a1548acc61a162ae > > 100644 > > --- a/drivers/gpu/drm/bridge/Kconfig > > +++ b/drivers/gpu/drm/bridge/Kconfig > > @@ -303,6 +303,7 @@ config DRM_SII902X > > config DRM_SII9234 > > tristate "Silicon Image SII9234 HDMI/MHL bridge" > > depends on OF > > + select EXTCON > > Either this or 'depends on EXTCON || !EXTCON' Feels like depends is a better description so will change to it, thanks! Best regards, Henrik Grimler > > help > > Say Y here if you want support for the MHL interface. > > It is an I2C driver, that detects connection of MHL bridge > > -- > With best wishes > Dmitry >
