[OpenWrt-Devel] [PATCH] imx6: add I2C retries for ventana i2c1

[Petr Štetiar]

Tim Harvey <tharvey at gateworks.com> [2020-05-28 06:56:44]:

Hi,

> The GSC sitting on i2c1 can NAK I2C transactions if it is busy
> performing an ADC cycle. Allow enough retries to work around this.

this looks like you either need to keep in your own vendor tree or try to fix
properly upstream, thanks. So I'm not going to accept this as this would
become just another maintenance burden during kernel version bumps etc.

-- ynezz

> Signed-off-by: Tim Harvey <tharvey at gateworks.com>
> ---
>  ...x-add-retries-for-NAK-s-on-ventana-boards.patch | 42 ++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
>  create mode 100644 target/linux/imx6/patches-5.4/200-i2c-imx-add-retries-for-NAK-s-on-ventana-boards.patch
> 
> diff --git a/target/linux/imx6/patches-5.4/200-i2c-imx-add-retries-for-NAK-s-on-ventana-boards.patch b/target/linux/imx6/patches-5.4/200-i2c-imx-add-retries-for-NAK-s-on-ventana-boards.patch
> new file mode 100644
> index 0000000..5f45342
> --- /dev/null
> +++ b/target/linux/imx6/patches-5.4/200-i2c-imx-add-retries-for-NAK-s-on-ventana-boards.patch
> @@ -0,0 +1,42 @@
> +From be183fc2af49e6020bb0b1ac8359351707383f63 Mon Sep 17 00:00:00 2001
> +From: Tim Harvey <tharvey at gateworks.com>
> +Date: Tue, 12 May 2020 12:41:32 -0700
> +Subject: [PATCH] i2c: imx: add retries for NAK's on ventana boards
> +
> +Ventana boards have a Gateworks System Controller (gsc) module that can
> +nak i2c transactions when its busy in an ADC loop. In order to not have to
> +hack up the pca953x and ds1672 device drivers which the GSC emulates we will
> +just add i2c retries around NAK's.
> +
> +Signed-off-by: Tim Harvey <tharvey at gateworks.com>
> +---
> + drivers/i2c/busses/i2c-imx.c | 6 ++++++
> + 1 file changed, 6 insertions(+)
> +
> +diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> +index a3b6133..b2378d8 100644
> +--- a/drivers/i2c/busses/i2c-imx.c
> ++++ b/drivers/i2c/busses/i2c-imx.c
> +@@ -467,6 +467,8 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
> + {
> + 	if (imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR) & I2SR_RXAK) {
> + 		dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
> ++		if (i2c_imx->adapter.retries)
> ++			return -EAGAIN;
> + 		return -ENXIO;  /* No ACK */
> + 	}
> + 
> +@@ -1097,6 +1099,10 @@ static int i2c_imx_probe(struct platform_device *pdev)
> + 	i2c_imx->adapter.dev.of_node	= pdev->dev.of_node;
> + 	i2c_imx->base			= base;
> + 	ACPI_COMPANION_SET(&i2c_imx->adapter.dev, ACPI_COMPANION(&pdev->dev));
> ++	if (of_machine_is_compatible("gw,ventana") && phy_addr == 0x021a0000) {
> ++		dev_info(&pdev->dev, "Adding retries for Ventana GSC\n");
> ++		i2c_imx->adapter.retries = 3;
> ++	}
> + 
> + 	/* Get I2C clock */
> + 	i2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
> +-- 
> +2.7.4

_______________________________________________
openwrt-devel mailing list
openwrt-devel at lists.openwrt.org
https://lists.openwrt.org/mailman/listinfo/openwrt-devel