On Sun, Mar 26, 2017 at 11:22:57AM +0200, Geert Uytterhoeven wrote: > Hi Russell, Sjoerd, > > On Fri, Mar 24, 2017 at 5:42 PM, Russell King - ARM Linux > <linux@xxxxxxxxxxxxxxx> wrote: > > On Fri, Mar 24, 2017 at 05:26:32PM +0100, Sjoerd Simons wrote: > >> When testing on a Renesas board with the PL010 serial driver enabled > >> serial output broke. Turns out the minor device numbers for both > >> drivers happen to overlap, causing whichever driver happened to be the > >> second one to register to fail. > > > > How the **** has the SH serial driver ended up with overlapping device > > numbers? > > Interesting... > > > What happened to our maintained list of allocated major/minor device > > numbers, which is supposed to stop crap like this happening? > > AMBA PL010 has been assigned major 204, minors 16..31, > SCI has been assigned major 204, minors 8..11. > > Over the years, Renesas SoCs have been gaining more and more serial > ports, leading to > > #define SCI_NPORTS CONFIG_SERIAL_SH_SCI_NR_UARTS > > with CONFIG_SERIAL_SH_SCI_NR_UARTS=20 in shmobile_defconfig and > multi_v7_defconfig (although the maximum value on any supported SoC is 18). > > But once the value becomes 5 or more, it starts overflowing into the ttyFWx > and ttyAMx space. > > How to solve this? > Time for the serial subsystem to switch to dynamic minors, and get rid of the > what-is-your-serial-port-called-again-on-this-platform > multi-million-euro question? Yes, please, we need to do that. Let's provide a build option for it, like USB has had for over a decade. If it's enabled, it's all dynamic, if not, the "old style" ones are used. Then we don't accept any new reservations, making new drivers use the dynamic number, and over a long time, all should be good. thanks, greg k-h
