Messages in this thread | | | Date | Tue, 14 Jun 2022 20:09:12 +0530 | Subject | Re: [PATCHv15 5/9] lib: Add register read/write tracing support | From | Sai Prakash Ranjan <> |
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On 6/14/2022 8:02 PM, Steven Rostedt wrote: > On Wed, 18 May 2022 22:14:14 +0530 > Sai Prakash Ranjan <quic_saipraka@quicinc.com> wrote: > >> From: Prasad Sodagudi <psodagud@codeaurora.org> >> >> Generic MMIO read/write i.e., __raw_{read,write}{b,l,w,q} accessors >> are typically used to read/write from/to memory mapped registers >> and can cause hangs or some undefined behaviour in following few >> cases, >> >> * If the access to the register space is unclocked, for example: if >> there is an access to multimedia(MM) block registers without MM >> clocks. >> >> * If the register space is protected and not set to be accessible from >> non-secure world, for example: only EL3 (EL: Exception level) access >> is allowed and any EL2/EL1 access is forbidden. >> >> * If xPU(memory/register protection units) is controlling access to >> certain memory/register space for specific clients. >> >> and more... >> >> Such cases usually results in instant reboot/SErrors/NOC or interconnect >> hangs and tracing these register accesses can be very helpful to debug >> such issues during initial development stages and also in later stages. >> >> So use ftrace trace events to log such MMIO register accesses which >> provides rich feature set such as early enablement of trace events, >> filtering capability, dumping ftrace logs on console and many more. >> >> Sample output: >> >> rwmmio_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 >> rwmmio_post_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 >> rwmmio_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 addr=0xfffffbfffdbff610 >> rwmmio_post_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 val=0x0 addr=0xfffffbfffdbff610 >> >> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org> >> Co-developed-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com> >> Signed-off-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com> >> --- > From a tracing point of view, I do not see anything wrong with this patch. > > Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> > > -- Steve
Thanks Steve.
Hi Arnd, I hope we can take this series in your tree or let me know if anything else is pending?
Thanks, Sai
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