| Message ID | 20220203171114.10888-1-erwan.leray@foss.st.com |
|---|---|
| Headers | show |
| Series | STM32 configure UART nodes for DMA | expand |
Hi Uwe, We found the issue, thank you to have reported it. stm32-usart driver was not tolerant to a probe defer from DMA when the earlycon is active. You can find the patch here: https://lore.kernel.org/lkml/20221118170602.1057863-1-valentin.caron@foss.st.com/ Valentin On 11/9/22 14:48, Amelie Delaunay wrote: > On 11/8/22 16:28, Marek Vasut wrote: >> On 11/8/22 12:59, Uwe Kleine-König wrote: >>> On Fri, Feb 04, 2022 at 04:41:55PM +0100, Erwan LE RAY wrote: >>>> On 2/4/22 2:22 PM, Alexandre TORGUE wrote: >>>>> Hi Ahmad >>>>> >>>>> On 2/3/22 18:25, Ahmad Fatoum wrote: >>>>>> Hello Erwan, >>>>>> >>>>>> On 03.02.22 18:10, Erwan Le Ray wrote: >>>>>>> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and >>>>>>> remove it at board level to keep current PIO behavior when needed. >>>>>>> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7 >>>>>>> (no HW flow control pin available) are kept in PIO mode, while >>>>>>> USART3 >>>>>>> is now configured in DMA mode. >>>>>>> UART4 (console UART) has to be kept in irq mode, as DMA support for >>>>>>> console has been removed from the driver by commit e359b4411c28 >>>>>>> ("serial: stm32: fix threaded interrupt handling"). >>>>>> >>>>>> Do I understand correctly that your first patch breaks consoles of >>>>>> most/all boards, because they will briefly use DMA, which is refused >>>>>> by the stm32-usart driver and then you add a patch for each board >>>>>> to fix that breakage? >>>>> >>>>> We have two solutions and both have pro/drawbacks. The first one >>>>> (Erwan >>>>> ones, can break the boot if the patch is taken "alone". Your >>>>> proposition >>>>> avoids this breakage but deletes a non define property (which is a >>>>> bit >>>>> weird). However I prefer to keep a functional behavior, and keep >>>>> Ahmad >>>>> proposition. Ahmad, just one question, dt-bindings check doesn't >>>>> complain about it ? >>>>> >>>>> Cheers >>>>> Alex >>>>> >>>>>> >>>>>> Such intermittent breakage makes bisection a hassle. >>>>>> /delete-property/ >>>>>> is a no-op when the property doesn't exist, so you could move the >>>>>> first >>>>>> patch to the very end to avoid intermittent breakage. >>>>>> >>>>>> I also think that the driver's behavior is a bit harsh. I think >>>>>> it would >>>>>> be better for the UART driver to print a warning and fall back to >>>>>> PIO for console instead of outright refusing and rendering the >>>>>> system >>>>>> silent. That's not mutually exclusive with your patch series here, >>>>>> of course. >>>>>> >>>>>> Cheers, >>>>>> Ahmad >>>>>> >>>> >>>> The driver implementation will consider the request to probe the UART >>>> console in DMA mode as an error (-ENODEV), and will fallback this >>>> UART probe >>>> in irq mode. >>> >>>> Whatever the patch ordering, the boot will never be broken. The >>>> board dt >>>> patches aim to get a "proper" implementation, but from functional >>>> perspective the driver will manage a request to probe an UART >>>> console in DMA >>>> mode as an error and fall it back in irq mode. >>> >>> I didn't debug this further yet, but my machine (with an out-of-tree >>> dts) fails to boot 6.1-rc4 without removing the dma properties from the >>> console UART. This is a bug isn't it? The same dts created a working >>> setup with stm32mp157.dtsi from 5.15 + kernel 5.15. > > Hi Uwe, > > Could you confirm earlycon is enabled on your setup? > > Without earlycon, boot is ok, even with dma properties, at least on > stm32mp157c-dk2. > >>> >>> I can debug this further, but maybe you know off-hand what the problem >>> is? >> >> +CC Amelie, as this might be related to the DMA series that landed >> recently: >> >> $ git log --oneline v5.18..v6.0 -- drivers/dma/stm32* > > Hi Marek, > > We haven't yet investigated the issue, and if latest DMA updates could > explain why earlycon breaks the boot. > > > +TO Valentin, as he's now in charge of UART driver. > Valentin and I will investigate this issue. > > Regards, > Amelie
Add DMA configuration to UART nodes in stm32mp15x (SOC level) and remove it at board level to keep current PIO behavior when needed. For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7 (no HW flow control pin available) are kept in PIO mode, while USART3 is now configured in DMA mode. UART4 (console UART) has to be kept in irq mode, as DMA support for console has been removed from the driver by commit e359b4411c28 ("serial: stm32: fix threaded interrupt handling"). For other stm32mp15x-based boards, current configuration is kept for all UART instances. Erwan Le Ray (16): ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151 ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1 ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2 ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2 ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7 ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0 ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96 ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1 ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02 ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2 ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-picoitx ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcor-avenger96 arch/arm/boot/dts/stm32mp151.dtsi | 21 +++++++++++++++++++ .../stm32mp157a-icore-stm32mp1-ctouch2.dts | 2 ++ .../stm32mp157a-icore-stm32mp1-edimm2.2.dts | 2 ++ arch/arm/boot/dts/stm32mp157a-iot-box.dts | 2 ++ ...157a-microgea-stm32mp1-microdev2.0-of7.dts | 4 ++++ ...32mp157a-microgea-stm32mp1-microdev2.0.dts | 4 ++++ arch/arm/boot/dts/stm32mp157a-stinger96.dtsi | 6 ++++++ arch/arm/boot/dts/stm32mp157c-ed1.dts | 2 ++ arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts | 2 ++ arch/arm/boot/dts/stm32mp157c-odyssey.dts | 2 ++ .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi | 4 ++++ arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi | 4 ++++ .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi | 4 ++++ arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi | 2 ++ .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi | 6 ++++++ arch/arm/boot/dts/stm32mp15xx-dkx.dtsi | 4 ++++ 16 files changed, 71 insertions(+)