of-flash: Unable to ioremap() both 128MB NOR flashes on 32-bit system with 2GB+ RAM
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From: Kyle Moffett on 24 Jun 2010 23:50 Hello, I've got a new P2020 (32bit mpc85xx family) board I'm working on a port for that includes 2 NOR flashes (128MB each) and a removable SO-RDIMM of 2GB or 4GB. Unfortunately when I configure both flashes in the device-tree off my elbc, Linux is completely unable to access the second one because it attempts to ioremap() the entire virtual address space of both FLASH chips. Even with only one flash chip enabled, there's a bit of a noticeable performance degradation because the mapping consumes almost all of my available vmalloc space and forces bounce-buffering for all my HIGHMEM. It looks like the "of-flash" driver currently requires that the whole chip be mapped in the kernel at once. I would much rather have a 50% performance penalty on flash accesses (which are already very slow) and regain most of the vmap space. So the question is, is there a way to convince the MTD layer to iomap() only what it needs to access to do reads and writes? If not, what changes would need to be made to MTD and/or "of-flash" to create such functionality? Cheers, Kyle Moffett -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |