Messages in this thread |  | | From | Esben Haabendal <> | Subject | Re: [PATCH] serial: 8250: Add support for using platform_device resources | Date | Tue, 14 May 2019 14:02:40 +0200 |
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Andy Shevchenko <andy.shevchenko@gmail.com> writes:
> On Tue, May 14, 2019 at 12:23 PM Andy Shevchenko > <andy.shevchenko@gmail.com> wrote: >> On Tue, May 14, 2019 at 10:24 AM Esben Haabendal <esben@haabendal.dk> 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
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