On Fri, Apr 9, 2021 at 2:20 PM Philippe Mathieu-Daudé <f4...@amsat.org> wrote: > > +Paolo/Thomas > > On 4/9/21 7:21 PM, Patrick Venture wrote: > > On Fri, Apr 9, 2021 at 9:51 AM Philippe Mathieu-Daudé <f4...@amsat.org> > > wrote: > >> > >> Hi Patrick, > >> > >> On 4/9/21 6:25 PM, Patrick Venture wrote: > >>> The pca954x is an i2c mux, and this adds support for two variants of > >>> this device: the pca9546 and pca9548. > >>> > >>> This device is very common on BMCs to route a different channel to each > >>> PCIe i2c bus downstream from the BMC. > >>> > >>> Signed-off-by: Patrick Venture <vent...@google.com> > >>> Reviewed-by: Hao Wu <wuhao...@google.com> > >>> Reviewed-by: Havard Skinnemoen <hskinnem...@google.com> > >>> --- > >>> MAINTAINERS | 6 + > >>> hw/i2c/Kconfig | 4 + > >>> hw/i2c/i2c_mux_pca954x.c | 290 +++++++++++++++++++++++++++++++ > >>> hw/i2c/meson.build | 1 + > >>> hw/i2c/trace-events | 5 + > >>> include/hw/i2c/i2c_mux_pca954x.h | 19 ++ > >>> 6 files changed, 325 insertions(+) > >>> create mode 100644 hw/i2c/i2c_mux_pca954x.c > >>> create mode 100644 include/hw/i2c/i2c_mux_pca954x.h > >> > >>> diff --git a/hw/i2c/Kconfig b/hw/i2c/Kconfig > >>> index 09642a6dcb..8d120a25d5 100644 > >>> --- a/hw/i2c/Kconfig > >>> +++ b/hw/i2c/Kconfig > >>> @@ -28,3 +28,7 @@ config IMX_I2C > >>> config MPC_I2C > >>> bool > >>> select I2C > >>> + > >>> +config PCA954X > >>> + bool > >>> + select I2C > >> > >> Do you have a circular dependency when also using: > >> > >> depends on I2C > >> > >> ? > > > > I'm somewhat new to qemu -- I don't know what you mean, since I2C > > doesn't depend on pca954x, I don't imagine there could be a circular > > dependency. > > See > https://qemu-project.gitlab.io/qemu/devel/kconfig.html#guidelines-for-writing-kconfig-files > > PCA954X is plugged on an I2C bus > -> depends on I2C > > PCA954X provides I2C buses > -> select I2C
So from the guide it looks like my KConfig should have _depends_ on I2C. My board that I'm testing with selects PCA954X and doesn't explicitly select I2C. My device _does_ provide I2C buses, as you say. > > Your device is a particular case consuming and providing the Kconfig > 'I2C' symbol. I expect a circular dependency problem. Easy to test with > your series but I haven't. > > I suppose in this case, the "select" takes over on "depends on" so this > is OK. I have to imagine there is a similar situation for PCIe bridges, as they depend on PCI but also provide it. > > Now (unrelated to your series) thinking at the graphical Kconfig tree > representation (like this one generated 2 years ago: > https://drive.google.com/open?id=1kvwl7guuAmCh2Y2UqeXynlA2HmjWcRs9), > I'd rather see a circular dep. > > Regards, > > Phil.
