On Tue, May 14, 2019 at 02:02:40PM +0200, Esben Haabendal wrote: > Andy Shevchenko <andy.shevchenko@xxxxxxxxx> writes: > > > On Tue, May 14, 2019 at 12:23 PM Andy Shevchenko > > <andy.shevchenko@xxxxxxxxx> wrote: > >> On Tue, May 14, 2019 at 10:24 AM Esben Haabendal <esben@xxxxxxxxxxxx> wrote: > > > >> > Please take a look at https://lkml.org/lkml/2019/4/9/576 > >> > ("[PATCH v2 2/4] mfd: ioc3: Add driver for SGI IOC3 chip") > >> > >> Thank you for this link. > >> Now, look at this comment: > >> > >> + /* > >> + * Map all IOC3 registers. These are shared between subdevices > >> + * so the main IOC3 module manages them. > >> + */ > >> > >> Is it your case? Can we see the code? > > > > They do not request resources by the way. > > Actually, that looks like a bug in ioc3.c driver. Nope. This is the right thing to do. > It is using mfd_add_devices() with a mem_base that has not been properly > requested, and the platform_get_resource() calls made by child drivers > does not guarantee exclusive access to the memory resources, as they are > not inserted in the root memory resource tree. Should platform_get_resource() guarantee that? I think no, otherwise entire MFD and other logic will collapse. > > You may do the same, I told you this several times. > > In drivers/mfd/ioc3.c: > > First, the uart resources are defined. The register memory resource is > defined relative to the mfd driver memory resource. > > +static struct resource ioc3_uarta_resources[] = { > + DEFINE_RES_MEM(offsetof(struct ioc3, sregs.uarta), > + sizeof_field(struct ioc3, sregs.uarta)), > + DEFINE_RES_IRQ(6) > +}; > > This is then used when creating the uart cell. > > + cell->name = "ioc3-serial8250"; > + cell->id = ioc3_serial_id++; > + cell->resources = ioc3_uarta_resources; > + cell->num_resources = ARRAY_SIZE(ioc3_uarta_resources); > > Finally, the mfd_add_devices() call is made, giving the resource for the > BAR0 region (&ipd->pdev->resource[0]) as mem_base argument: > > + mfd_add_devices(&ipd->pdev->dev, -1, ioc3_mfd_cells, > + cell - ioc3_mfd_cells, &ipd->pdev->resource[0], > + 0, ipd->domain); > > This is just what I want to do. > > But in order to guarantee exclusive access to the memory resource, I > need to have it requested. Here the root of our misunderstanding each other. Every driver till now works fine and entire model works fine without resources being requested. I told you already that if you want your way that has to be done not in 8250 driver, but in generic code (driver core or even resource framework). -- With Best Regards, Andy Shevchenko
