Messages in this thread | | | Subject | Re: [PATCH v14 1/2] drivers/coresight: Add UltraSoc System Memory Buffer driver | From | hejunhao <> | Date | Thu, 24 Nov 2022 21:33:01 +0800 |
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On 2022/11/23 22:03, Suzuki K Poulose wrote: > On 23/11/2022 12:38, Junhao He wrote: >> From: Qi Liu <liuqi115@huawei.com> >> >> Add driver for UltraSoc SMB(System Memory Buffer) device. >> SMB provides a way to buffer messages from ETM, and store >> these "CPU instructions trace" in system memory. >> The SMB device is identifier as ACPI HID "HISI03A1". Device >> system memory address resources are allocated using the _CRS >> method and buffer modes is the circular buffer mode. >> >> SMB is developed by UltraSoc technology, which is acquired by >> Siemens, and we still use "UltraSoc" to name driver. >> >> Signed-off-by: Qi Liu <liuqi115@huawei.com> >> Signed-off-by: Junhao He <hejunhao3@huawei.com> >> Tested-by: JunHao He <hejunhao3@huawei.com> >> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> >> --- >> drivers/hwtracing/coresight/Kconfig | 12 + >> drivers/hwtracing/coresight/Makefile | 1 + >> drivers/hwtracing/coresight/ultrasoc-smb.c | 658 +++++++++++++++++++++ >> drivers/hwtracing/coresight/ultrasoc-smb.h | 129 ++++ >> 4 files changed, 800 insertions(+) >> create mode 100644 drivers/hwtracing/coresight/ultrasoc-smb.c >> create mode 100644 drivers/hwtracing/coresight/ultrasoc-smb.h >> > >> +static void smb_sync_perf_buffer(struct smb_drv_data *drvdata, >> + struct cs_buffers *buf, >> + unsigned long head, >> + unsigned long data_size) >> +{ >> + struct smb_data_buffer *sdb = &drvdata->sdb; >> + char **dst_pages = (char **)buf->data_pages; >> + unsigned long to_copy; >> + long pg_idx, pg_offset; >> + >> + pg_idx = head >> PAGE_SHIFT; >> + pg_offset = head & (PAGE_SIZE - 1); >> + >> + while (data_size) { >> + unsigned long pg_space = PAGE_SIZE - pg_offset; >> + >> + /* Copy parts of trace data when read pointer wrap around */ >> + if (sdb->rd_offset + pg_space > sdb->buf_size) >> + to_copy = sdb->buf_size - sdb->rd_offset; >> + else >> + to_copy = min(data_size, pg_space); >> + >> + memcpy(dst_pages[pg_idx] + pg_offset, >> + sdb->buf_base + sdb->rd_offset, to_copy); >> + >> + pg_offset += to_copy; >> + if (pg_offset >= PAGE_SIZE) { >> + pg_offset = 0; >> + pg_idx++; >> + pg_idx %= buf->nr_pages; >> + } >> + data_size -= to_copy; >> + sdb->rd_offset += to_copy; >> + sdb->rd_offset %= sdb->buf_size; >> + } >> + >> + sdb->data_size = 0; > > > --8>-- cut here --<8-- > >> + writel(sdb->start_addr + sdb->rd_offset, >> + drvdata->base + SMB_LB_RD_ADDR_REG); >> + >> + /* >> + * Data remained in link cannot be purged when SMB is full, so >> + * synchronize the read pointer to write pointer, to make sure >> + * these remained data won't influence next trace. >> + */ >> + if (sdb->full) { >> + smb_purge_data(drvdata); >> + writel(readl(drvdata->base + SMB_LB_WR_ADDR_REG), >> + drvdata->base + SMB_LB_RD_ADDR_REG); >> + } > > --<8-- end here --8>-- > > As pointed out in the last review, we must do this step > everytime for perf mode irrespective of whether the buffer > was "FULL" or not. > > i.e, the above block should simply be: > > if (sdb->full) > smb_purge_data(drvdata); > > /* > * The uncollected Data must be discarded for perf, > * as it cannot be clubbed with next schedule. We > * any way TRUNCATE the buffer in this case. > */ > writel(readl(drvdata->base + SMB_LB_WR_ADDR_REG), > drvdata->base + SMB_LB_RD_ADDR_REG); > > Suzuki
Hi Suzuki,
We need to update SMB_LB_RD_ADDR_REG register first, then check the "full" flag, whether the register needs to be updated again.
If we don`t update the value of SMB_LB_RD_ADDR_REG register or reset buffer state, the buffer state will still be "full". The buffer has not free area,so the data will still remain in link.
Thanks. HeJunhao.
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