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Mon, 13 Apr 2026 09:19:59 -0700 (PDT) Message-ID: <3e45cbb7-70a6-438b-972e-f6f16a73cee5@gmail.com> Date: Tue, 14 Apr 2026 00:19:50 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: yangyccccc@gmail.com, "jonathan.cameron@huawei.com" , "alexander.shishkin@linux.intel.com" , Sanman Pradhan , shenyang39@huawei.com, prime.zeng@hisilicon.com Subject: Re: [PATCH 2/2] hwtracing: hisi_ptt: Remove unnecessary trace buffer zeroing in trace_start() To: "Pradhan, Sanman" , "linux-kernel@vger.kernel.org" References: <20260409010704.383882-1-sanman.pradhan@hpe.com> <20260409010704.383882-3-sanman.pradhan@hpe.com> From: Yicong Yang In-Reply-To: <20260409010704.383882-3-sanman.pradhan@hpe.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2026/4/9 09:07, Pradhan, Sanman wrote: > From: Sanman Pradhan > > hisi_ptt_trace_start() clears all four trace buffers before enabling > tracing. > > This is unnecessary. On trace stop, hisi_ptt_update_aux() copies only > the number of bytes reported in HISI_PTT_TRACE_WR_STS. On buffer-full > interrupts, it copies a full completed buffer. In both cases the driver > only consumes data written by hardware. > > Remove the buffer clearing from the trace start path. > > Signed-off-by: Sanman Pradhan Reviewed-by: Yicong Yang > --- > drivers/hwtracing/ptt/hisi_ptt.c | 5 ----- > 1 file changed, 5 deletions(-) > > diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c > index 73b93df8504c4..cbfbd1f146ba3 100644 > --- a/drivers/hwtracing/ptt/hisi_ptt.c > +++ b/drivers/hwtracing/ptt/hisi_ptt.c > @@ -195,7 +195,6 @@ static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt) > struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl; > u32 val; > int ret; > - int i; > > /* Check device idle before start trace */ > if (!hisi_ptt_wait_trace_hw_idle(hisi_ptt)) { > @@ -221,10 +220,6 @@ static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt) > /* Reset the index of current buffer */ > hisi_ptt->trace_ctrl.buf_index = 0; > > - /* Zero the trace buffers */ > - for (i = 0; i < HISI_PTT_TRACE_BUF_CNT; i++) > - memset(ctrl->trace_buf[i].addr, 0, HISI_PTT_TRACE_BUF_SIZE); > - > /* Clear the interrupt status */ > writel(HISI_PTT_TRACE_INT_STAT_MASK, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT); > writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_INT_MASK);