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.kesavan@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;