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. 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. > 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. /Esben
