HI Prabhakar, > -----Original Message----- > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx> > Sent: 13 January 2025 17:00 > Subject: Re: [PATCH v3 0/6] Add support to retrieve the bootstatus from watchdog for RZ/V2H(P) SoC > > Hi Biju, > > On Mon, Jan 13, 2025 at 4:43 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote: > > > > Hi Prabhakar, > > > > > -----Original Message----- > > > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx> > > > Sent: 13 January 2025 16:29 > > > Subject: Re: [PATCH v3 0/6] Add support to retrieve the bootstatus > > > from watchdog for RZ/V2H(P) SoC > > > > > > Hi Guenter, > > > > > > On Mon, Jan 13, 2025 at 4:0 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > > > > > > > On 1/13/25 04:40, Lad, Prabhakar wrote: > > > > > Hi Biju, > > > > > > > > > > On Mon, Jan 13, 2025 at 11:38 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote: > > > > >> > > > > >> Hi Prabhakar, > > > > >> > > > > >>> -----Original Message----- > > > > >>> From: Prabhakar <prabhakar.csengg@xxxxxxxxx> > > > > >>> Sent: 13 January 2025 11:24 > > > > >>> Subject: [PATCH v3 0/6] Add support to retrieve the bootstatus > > > > >>> from watchdog for RZ/V2H(P) SoC > > > > >>> > > > > >>> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> > > > > >>> > > > > >>> Hi All, > > > > >>> > > > > >>> This patch series adds SYSCON support to retrieve boot status information for RZ/V2H(P) SoC. > > > > >>> Summary of Changes, > > > > >>> > > > > >>> Clock: > > > > >>> Add syscon compatible support to the CPG block in bindings and > > > > >>> device trees. > > > > >>> > > > > >>> Watchdog: > > > > >>> Document the renesas,r9a09g057-syscon-wdt-errorrst property. > > > > >>> Update the watchdog driver to fetch and report boot status via > > > > >>> Error Reset Registers (CPG_ERROR_RSTm). > > > > >>> > > > > >>> Device Tree: > > > > >>> Add the syscon property to CPG and WDT nodes in R9A09G057 and > > > > >>> R9A09G047 SoC DTSI. > > > > >>> > > > > >>> These changes enable the watchdog driver to identify boot > > > > >>> sources like Power-on Reset and Watchdog Reset, improving system diagnostics. > > > > >> > > > > >> This means that, we should assume U-boot/bootloader should not clear the WDT reset status > bit. > > > > >> > > > > >> If they clear it, there should be a way to propagate it from > > > > >> u-boot/bootloader to linux, otherwise, we get wrong bootstatus in linux. > > > > >> But the clearing of watchdog status by one of the cases: > > > > >> > > > > >> 1) u-boot identify the boot source and clear the status bit > > > > >> > > > > > I agree, if the tf-a/u-boot clears the register, the bootstatus > > > > > reported by Linux will be in-correct. > > > > > > > > > > > > > I would rephrase that: Today, the boot status is _always_ > > > > incorrect if a reboot was triggered by a watchdog reset. After > > > > this patch, it will be correct unless the boot loader resets the status bit. > > > > > > > Agreed. > > > > > > > > Alternative solution, would be: > > > > > > > > > > Let the TF-A create WDT nodes for us and add a property > > > > > `renesas,r9a09g057-wdt-bootstatus` and propagate the WDT nodes > > > > > to Linux. > > > > > > > > > > renesas,r9a09g057-wdt-bootstatus = <0/1>; > > > > > > > > > > > > > That would require both a property change as well as a change in the bootloader. > > > > I suspect it would also be inappropriate as standard property and > > > > would have to be passed as 'chosen' property (if that is even > > > > permitted) or as command line argument. > > > > > > > > Either case, if the boot loader has to be changed anyway, why not > > > > just tell it to leave the boot status alone ? > > > > > > > It can be done, I think Biju is concerned about the user clearing > > > it, maybe using the `mw` command or the Linux CPG driver clearing it during the probe. > > > > If either TF-A or U-boot clears the status we have problem. We need to > > provide input to stake holders of u-boot/tf-a to not to clear the wdt > > boot status, so that linux can report correct status. > > > I think this can be done, currently the TF-A nor u-boot clears the status. Are you OK with this > approach? Yes. As it provides consistent wdt status in tf-a/u-boot/kernel. Cheers, Biju
