Hi Andy, Bin,
> -----"Andy Shevchenko" <[email protected]> schrieb: ----- > On Thu, Apr 2, 2020 at 7:55 AM Bin Meng <[email protected]> wrote: > > On Thu, Apr 2, 2020 at 1:55 AM Simon Glass <[email protected]> wrote: > > > On Wed, 1 Apr 2020 at 11:39, Andy Shevchenko <[email protected]> > > > wrote: > > > > On Wed, Apr 01, 2020 at 10:56:26AM -0600, Simon Glass wrote: > > > > > On Wed, 1 Apr 2020 at 08:45, Andy Shevchenko > > > > > <[email protected]> wrote: > > > > > > On Wed, Apr 1, 2020 at 5:32 PM Bin Meng <[email protected]> wrote: > > > > > > > On Wed, Apr 1, 2020 at 9:58 PM Andy Shevchenko > > > > > > > <[email protected]> wrote: > > > > > > > > > > > > > > > > The commit breaks serial console on the Intel Edison. > > > > > > > > > > > > > > > > This reverts commit 720f9e1fdb0c92d3fd16e1bfc25bcbd35612675c. > > > > > > > > > > > > > > > > Signed-off-by: Andy Shevchenko > > > > > > > > <[email protected]> > > > > > > > > --- > > > > > > > > drivers/serial/ns16550.c | 40 > > > > > > > > ++++++++++++---------------------------- > > > > > > > > 1 file changed, 12 insertions(+), 28 deletions(-) > > > > > > > > > > > > > > > > > > > > > > Could you please spend some time to investigate why this breaks > > > > > > > Intel Edison? > > > > > > > > > > > > > > Reverting this patch would mean we break other boards too as > > > > > > > Wolfgang's patch wanted to fix the breakage in the first place. > > > > > > > Much > > > > > > > appreciated! > > > > > > > > > > > > I guess I'm wrong person here. The DM code is a complete black box > > > > > > to me. > > > > > > Nevertheless, I may test any provided fix / debug / etc patch by > > > > > > request. > > > > > > > > > > > > And I think it's fair to investigate by the one who made a > > > > > > regression > > > > > > in the first place. > > > > > > > > > > Given that we have conflicting breakages, we need to debug Edison. > > > > > > > > I would glad to test any suggested change or debug patch! > > > > > > > > > Does it enable the debug UART? > > > > > > > > If I am not mistaken, it does not. > > > > > > Looks like you are right. If you know the address you could do that - > > > see minnowmax for an example. > > > > Please suggest what's the best approach to proceed. > > I think I understand what happened, and Wolfgang's patch *is* a culprit. > > In serial_intel_mid.c we setup a divisor before probing the actual > device. Now, since the address retrieving has been moved further in > the initialization, we are writing to unknown registers and thus don't > properly initialize hardware. Yes, you are right, mid_serial_probe() relies on plat->base being set by ns16550_serial_ofdata_to_platdata(). I was not aware that other drivers rely on ns16550 in this way. And now that I know I see that there are few more: $ grep -r -l --include='*.c' -e ns16550_serial_probe -e ns16550_serial_ofdata_to_platdata drivers/serial/serial_intel_mid.c drivers/serial/serial_rockchip.c drivers/serial/serial_omap.c drivers/serial/ns16550.c arch/x86/cpu/apollolake/uart.c arch/x86/cpu/slimbootloader/serial.c This means my patch has a wider impact than what I have taken care of. @Bin: I'm fine with reverting 720f9e1 for now. I will come back with a new revision of this patch when I had the time to look at the other impacted drivers. But reverting 720f9e1 is IMHO only a temporary workaround, as the underlying problem (possible PCI access in ofdata_to_platdata()) should be fixed anyway, at least my interpretation of the comment in drivers/pci/pci-uclass.c is that this PCI access should not be there: "A common cause of this problem is that this function is called in the ofdata_to_platdata() method of @dev. Accessing the PCI bus in that method is not allowed, since it has not yet been probed. To fix this, move that access to the probe() method of @dev instead." @Andy: Regarding serial_intel_mid: I don't know the hardware, but would it be possible to move the register accesses after the call to ns16550_serial_probe()? mid_writel(plat, UART_MUL, 96); mid_writel(plat, UART_DIV, 125); mid_writel(plat, UART_PS, 16); return ns16550_serial_probe(dev); > So, the proper fix would be in my opinion to introduce a call back or > some other way to make ordering possible, like registering hw_init > callback in probe which will be called in the ns16550, or even do this > as a callback for all serial class drivers. > > I don't dare to dive into this anticipating that crap will hit the fan. > So, please, who is knowing serial code, fix this asap! regards, Wolfgang
