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Disconnect spi from gpio dependency
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This fixes frank-zago#29
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@mjsir911
mjsir911 committed Mar 12, 2024
1 parent 9d65db4 commit 793ea2f
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Showing 3 changed files with 2 additions and 10 deletions.
1 change: 1 addition & 0 deletions ch341-core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
static const struct mfd_cell ch341_devs[] = {
{ .name = "ch341-gpio", },
{ .name = "ch341-i2c", },
{ .name = "ch341-spi", },
};

static int ch341_usb_probe(struct usb_interface *iface,
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9 changes: 0 additions & 9 deletions gpio-ch341.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,10 +27,6 @@
#include <linux/usb.h>
#include <linux/version.h>

static const struct mfd_cell ch341_gpio_devs[] = {
{ .name = "ch341-spi", },
};

#define CH341_GPIO_NUM_PINS 16 /* Number of GPIO pins */

/* GPIO chip commands */
Expand Down Expand Up @@ -411,11 +407,6 @@ static int ch341_gpio_probe(struct platform_device *pdev)
return ret;
}

ret = mfd_add_hotplug_devices(&pdev->dev, ch341_gpio_devs,
ARRAY_SIZE(ch341_gpio_devs));
if (ret)
dev_warn(&pdev->dev, "Failed to add mfd SPI device to gpio.");

return 0;
}

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2 changes: 1 addition & 1 deletion spi-ch341.c
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Original file line number Diff line number Diff line change
Expand Up @@ -310,7 +310,7 @@ static void ch341_cleanup(struct spi_device *spi)

static int ch341_spi_probe(struct platform_device *pdev)
{
struct ch341_ddata *ch341 = dev_get_drvdata(pdev->dev.parent->parent);
struct ch341_ddata *ch341 = dev_get_drvdata(pdev->dev.parent);
struct spi_controller *master;
struct ch341_spi *dev;
int ret;
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2 comments on commit 793ea2f

@frank-zago
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But spi is a client of gpio. If spi is active, it uses some pins from gpio, which other applications must then not use.

@mjsir911
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@mjsir911 mjsir911 commented on 793ea2f Mar 13, 2024 •
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No other gpio drivers in the kernel tree right now load other drivers and what you're doing here causes an issue with deregistering devices as seen in frank-zago#29.

With the above changes, all that happens is:

  • no gpio driver loaded, loads spi driver:

      [10612.409431] ch341-spi ch341-spi.12.auto: CH341 SPI Controller: ch341-spi.12.auto
  [10612.409442] spi_master (null): cannot find GPIO chip ch341, deferring
  [10612.409468] ch341-spi ch341-spi.15.auto: CH341 SPI Controller: ch341-spi.15.auto
  [10612.409471] spi_master (null): cannot find GPIO chip ch341, deferring

  • loading gpio driver after spi driver works successfully

  • both drivers loaded, unloads gpio driver: rmmod: ERROR: Module gpio_ch341 is in use

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