Hi Abhilash,
Am Donnerstag, den 11.12.2014, 08:28 +0530 schrieb Abhilash Kesavan:
> Currently, the SRAM allocator returns device memory via ioremap.
> This causes issues on ARM64 when the internal SoC SRAM allocated by
> the generic sram driver is used for audio playback. The destination
> buffer address (which is ioremapped SRAM) is not 64-bit aligned for
> certain streams (e.g. 44.1k sampling rate). In such cases we get
> unhandled alignment faults. Use ioremap_wc in place of ioremap which
> gives us normal non-cacheable memory instead of device memory.
Could this break the omap_bus_sync() implementation in
arch/arm/mach-omap2/omap4-common.c?
void omap_bus_sync(void)
{
if (dram_sync && sram_sync) {
writel_relaxed(readl_relaxed(dram_sync), dram_sync);
writel_relaxed(readl_relaxed(sram_sync), sram_sync);
isb();
}
}
It is used in wmb() and omap_do_wfi() to drain interconnect write
buffers on omap4/5. If sram_sync is mapped with write-combining, could
the last write to sram_sync stay stuck in the write-combining buffer
until after the function returns?
regards
Philipp
> Signed-off-by: Abhilash Kesavan <a.kesa...@samsung.com>
> ---
> This is based on the discussion about the crash here:
> http://www.spinics.net/lists/arm-kernel/msg384647.html
>
> drivers/misc/sram.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
> index 21181fa..15b4d4e 100644
> --- a/drivers/misc/sram.c
> +++ b/drivers/misc/sram.c
> @@ -69,12 +69,23 @@ static int sram_probe(struct platform_device *pdev)
> INIT_LIST_HEAD(&reserve_list);
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> - virt_base = devm_ioremap_resource(&pdev->dev, res);
> - if (IS_ERR(virt_base))
> - return PTR_ERR(virt_base);
> + if (!res) {
> + dev_err(&pdev->dev, "found no memory resource\n");
> + return -EINVAL;
> + }
>
> size = resource_size(res);
>
> + if (!devm_request_mem_region(&pdev->dev,
> + res->start, size, pdev->name)) {
> + dev_err(&pdev->dev, "could not request region for resource\n");
> + return -EBUSY;
> + }
> +
> + virt_base = devm_ioremap_wc(&pdev->dev, res->start, size);
> + if (IS_ERR(virt_base))
> + return PTR_ERR(virt_base);
> +
> sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
> if (!sram)
> return -ENOMEM;
--
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