From: Sven Van Asbroeck <thesven73@gmail.com>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Mark Brown <broonie@kernel.org>,
kernel list <linux-kernel@vger.kernel.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Discussions about the Letux Kernel
<letux-kernel@openphoenux.org>
Subject: Re: [BUG] SPI broken for SPI based panel drivers
Date: Tue, 1 Dec 2020 10:52:03 -0500 [thread overview]
Message-ID: <CAGngYiVd6d2pb3eOd5ZiCvTBOzZK6+dudRUVWj8neBRK0S42Pg@mail.gmail.com> (raw)
In-Reply-To: <6283C16F-549C-4463-BC08-E2C1A1D78B2F@goldelico.com>
Nikolaus,
On Tue, Dec 1, 2020 at 9:38 AM H. Nikolaus Schaller <hns@goldelico.com> wrote:
>
> Let's work on a fix for the fix now.
I tested spi-gpio on my system, by converting a built-in or hardware spi,
to a spi-gpio. Interestingly, the patch has the opposite effect on my system:
before the patch, spi-gpio did not work, but after it's applied, it does work.
Can you tell me the idle status of your chip-select gpio in debugfs?
# mount -t debugfs none /sys/kernel/debug
# cat /sys/kernel/debug/gpio
Look for something like this:
gpiochip0: GPIOs 0-31, parent: platform/209c000.gpio, 209c000.gpio:
gpio-17 ( |spi5 CS0 ) out hi ACTIVE LOW
Also, apply the following patch, and tell me
a) does this dev_err() get called on your system, and
b) what is the value when your chip is de-selected
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 7e8804b02be9..b2f4cf5c9ffb 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -813,11 +813,12 @@ static void spi_set_cs(struct spi_device *spi,
bool enable)
if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) {
if (!(spi->mode & SPI_NO_CS)) {
- if (spi->cs_gpiod)
+ if (spi->cs_gpiod) {
+ dev_err(&spi->dev, "gpiod %s", enable1
? "enable" : "disable");
/* polarity handled by gpiolib */
gpiod_set_value_cansleep(spi->cs_gpiod,
enable1);
- else
+ } else
/*
* invert the enable line, as active low is
* default for SPI.
next prev parent reply other threads:[~2020-12-01 15:52 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-30 19:03 [BUG] SPI broken for SPI based panel drivers H. Nikolaus Schaller
2020-11-30 20:13 ` Sven Van Asbroeck
2020-11-30 20:22 ` Sven Van Asbroeck
2020-12-01 8:59 ` H. Nikolaus Schaller
2020-12-01 12:16 ` Mark Brown
2020-12-01 14:05 ` H. Nikolaus Schaller
2020-12-01 14:20 ` Linus Walleij
2020-12-01 14:34 ` Sven Van Asbroeck
2020-12-01 14:35 ` H. Nikolaus Schaller
2020-12-01 15:52 ` Sven Van Asbroeck [this message]
2020-12-01 16:46 ` H. Nikolaus Schaller
2020-12-01 16:10 ` Sven Van Asbroeck
2020-12-01 16:39 ` H. Nikolaus Schaller
2020-12-01 16:53 ` Sven Van Asbroeck
2020-12-01 17:10 ` H. Nikolaus Schaller
2020-12-01 18:43 ` Sven Van Asbroeck
2020-12-02 12:19 ` Mark Brown
2020-12-04 10:08 ` H. Nikolaus Schaller
2020-12-04 13:46 ` Sven Van Asbroeck
2020-12-04 16:49 ` H. Nikolaus Schaller
2020-12-04 19:19 ` Sven Van Asbroeck
2020-12-04 21:31 ` H. Nikolaus Schaller
2020-12-05 0:25 ` Linus Walleij
2020-12-05 7:04 ` H. Nikolaus Schaller
2020-12-09 8:04 ` Andreas Kemnade
2020-12-09 8:40 ` H. Nikolaus Schaller
2020-12-09 8:38 ` Linus Walleij
2020-12-09 8:45 ` H. Nikolaus Schaller
2020-12-01 22:51 ` Linus Walleij
2020-12-01 16:44 ` [Letux-kernel] " Andreas Kemnade
2020-12-01 16:51 ` H. Nikolaus Schaller
2020-12-01 16:52 ` H. Nikolaus Schaller
2020-12-01 16:55 ` Sven Van Asbroeck
2020-12-01 16:20 ` Mark Brown
2020-12-01 16:41 ` H. Nikolaus Schaller
2020-12-01 17:11 ` Mark Brown
2020-12-01 12:41 ` Sven Van Asbroeck
2020-12-01 13:32 ` H. Nikolaus Schaller
2020-12-01 14:08 ` Sven Van Asbroeck
2020-12-01 15:33 ` Mark Brown
2020-12-05 20:57 ` Pavel Machek
2020-12-07 13:43 ` Mark Brown
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