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[217.233.226.177]) by smtp.gmail.com with ESMTPSA id md15-20020a170906ae8f00b0098d486d2bdfsm6944627ejb.177.2023.08.15.03.43.44 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 15 Aug 2023 03:43:44 -0700 (PDT) From: Leif Middelschulte X-Google-Original-From: Leif Middelschulte To: Thierry Reding , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team Cc: Leif Middelschulte , linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 3/4] pwm: imx27: verify decreasing PWM FIFO av value Date: Tue, 15 Aug 2023 12:43:31 +0200 Message-Id: <20230815104332.55044-3-Leif.Middelschulte@gmail.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) In-Reply-To: <20230815104332.55044-1-Leif.Middelschulte@gmail.com> References: <20230310174517.rb7xxrougkse2lrc@pengutronix.de> <20230815104332.55044-1-Leif.Middelschulte@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org Avoid unnecessary sleeps as adviced[0], if the FIFO cannot be emptied. [0] https://lore.kernel.org/lkml/20230310174517.rb7xxrougkse2lrc@pengutronix.de/T/#ec9560c1f613d9c0d7b77d72ad9051768812f80db Signed-off-by: Leif Middelschulte --- drivers/pwm/pwm-imx27.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c index c2a1e2030072..9673e809d212 100644 --- a/drivers/pwm/pwm-imx27.c +++ b/drivers/pwm/pwm-imx27.c @@ -126,7 +126,7 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip, struct device *dev = chip->dev; unsigned int period_ms = DIV_ROUND_UP_ULL(pwm->state.period, NSEC_PER_MSEC); int tries = MX3_PWM_FIFOAV_EMPTY_LOOP; - int fifoav; + int fifoav, previous_fifoav = INT_MAX; u32 sr; while (tries--) { @@ -134,6 +134,10 @@ static int pwm_imx27_wait_fifo_empty(struct pwm_chip *chip, fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr); if (fifoav == MX3_PWMSR_FIFOAV_EMPTY) return; + /* if the FIFO value does not decrease, there is another problem */ + if (previous_fifoav == fifoav) + break; + previous_fifoav = fifoav; msleep(period_ms); } dev_warn(dev, "FIFO has been refilled concurrently\n"); -- 2.39.2 (Apple Git-143)