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Mon, 04 May 2026 17:29:21 -0700 (PDT) Date: Mon, 4 May 2026 17:29:19 -0700 From: Dmitry Torokhov To: Andreas Kemnade Cc: Yuki Horii , clamor95@gmail.com, johannes.kirchmair@skidata.com, linux-input@vger.kernel.org Subject: Re: [PATCH] Input: touchscreen: tsc2007: Reduce I2C transactions for Z2 read Message-ID: References: <20260410074100.1660-1-horiiyuk@ishida.co.jp> <20260502125313.3e1c296a@kemnade.info> Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260502125313.3e1c296a@kemnade.info> On Sat, May 02, 2026 at 12:53:13PM +0200, Andreas Kemnade wrote: > Hi, > > On Sun, 19 Apr 2026 17:18:23 -0700 > Dmitry Torokhov wrote: > > > Hi Yuki, > > > > On Fri, Apr 10, 2026 at 04:41:00PM +0900, Yuki Horii wrote: > > > From: Yuki Horii > > > > > > The current implementation sends a separate power-down command > > > after reading the Z2 value, resulting in an extra I2C > > > transaction per measurement cycle. > > > > > > The TSC2007 command byte contains a 2-bit power-down mode > > > selection field. By selecting the power-down state in the Z2 > > > measurement command, the device powers down after the Z2 A/D > > > conversion completes, eliminating the subsequent power-down > > > transaction. > > > > > > This reduces the number of I2C transactions by one per touch > > > measurement cycle, decreasing I2C bus overhead and improving > > > touch sampling performance. > > > > > > Signed-off-by: Yuki Horii > > > --- > > > drivers/input/touchscreen/tsc2007_core.c | 6 ++---- > > > 1 file changed, 2 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/input/touchscreen/tsc2007_core.c b/drivers/input/touchscreen/tsc2007_core.c > > > index 948935de894b..ff60245baa96 100644 > > > --- a/drivers/input/touchscreen/tsc2007_core.c > > > +++ b/drivers/input/touchscreen/tsc2007_core.c > > > @@ -61,10 +61,8 @@ static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc) > > > > > > /* turn y+ off, x- on; we'll use formula #1 */ > > > tc->z1 = tsc2007_xfer(tsc, READ_Z1); > > > - tc->z2 = tsc2007_xfer(tsc, READ_Z2); > > > - > > > - /* Prepare for next touch reading - power down ADC, enable PENIRQ */ > > > - tsc2007_xfer(tsc, PWRDOWN); > > > + /* Read Z2 and power down ADC after A/D conversion, enable PENIRQ */ > > > + tc->z2 = tsc2007_xfer(tsc, (TSC2007_POWER_OFF_IRQ_EN | TSC2007_MEASURE_Z2)); > > > } > > > > > > u32 tsc2007_calculate_resistance(struct tsc2007 *tsc, struct ts_event *tc) > > > > Thank you for the patch. > > > > I'd like people using this part to chime in (CCed). > > > This looks like that there might be some reason behind it. But I cannot find any. > Either by reading the datasheet nor by testing. > > I have checked the interrupt counter. Output seems still be same. > Interrupts appear when finger is moving. > > So > Tested-by: Andreas Kemnade # GTA04 Thank you for giving it a spin Andreas. Applied, thank you Yuki. -- Dmitry