Hi Suzuki,
Now ETM4X driver use MMIO or system instruction depends on this check in function etm4_init_csdev_access:
if (drvdata->base) return etm4_init_iomem_access(drvdata, csa);
This check always true if firmware provides a address range in ACPI table of ETE, and as a result, the ETE device in this case cannot be successfully probed.
I think OS should be compatible with this situation, no matter firmware how to organize ETE information in ACPI table. How do you feel about it?
Thank you
Ruidong Tian 在 2023/10/18 16:28, Suzuki K Poulose 写道:
On 18/10/2023 08:05, Ruidong Tian wrote:
The ETM4X driver now assume that all ETE as CPU system instructions accessed device, in fact the ETE device on some machines also accessed via MMIO.
Signed-off-by: Ruidong Tian tianruidong@linux.alibaba.com
Why are we going backwards to MMIO from system instructions ? Is it because of an "unfriendly" hypervisor preventing access ?
As such, without a sufficiently acceptable explanation, I am reluctant to make this change
Suzuki
drivers/hwtracing/coresight/coresight-etm4x-core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 285539104bcc..ad298c9cc87e 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -1103,8 +1103,9 @@ static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata, * with MMIO. But we cannot touch the OSLK until we are * sure this is an ETM. So rely only on the TRCDEVARCH. */ - if ((devarch & ETM_DEVARCH_ID_MASK) != ETM_DEVARCH_ETMv4x_ARCH) { - pr_warn_once("TRCDEVARCH doesn't match ETMv4 architecture\n"); + if ((devarch & ETM_DEVARCH_ID_MASK) != ETM_DEVARCH_ETMv4x_ARCH && + (devarch & ETM_DEVARCH_ID_MASK) != ETM_DEVARCH_ETE_ARCH) { + pr_warn_once("TRCDEVARCH doesn't match ETMv4/ETE architecture\n"); return false; }