On 05/18/2011 08:04 AM, Dhoti Walla wrote: > Hello, > > I'm writing a driver for a PCI card and having some trouble accessing > the memory mapped registers on the board. > > I use: > > pci_resource_start(..) and pci_resource_len(..) to get the starting > address and size of the memory mapped registers. > pci_resource_flags(...) returns IORESOURCE_MEMORY and IORESOURCE_SHADOWABLE > > request_mem_region() and ioremap_nocache() both succeed. > > when I call iowrite32(...) to write a 4 byte value, it succeeds on the > first attempt. > when I call iowrite16(...) to write a 2 byte value, it succeeds on the > 2nd attempt (i.e I have to call iowrite16(..) twice before the write > happens) > when I call iowrite8(...) to write a 1 byte value, it succeeds on the > 4th attempt. > > I have no idea why 2 byte and 1 byte writes don't work on the first > attempt. It's probably the PCI posting. Try to read some register from the device after the write. BTW. you should not use iowrite*/ioread* on ioremap space. Either use iomap with ioread*/iowrite* or ioremap with write*/read*. regards, -- js _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
