Re: [PATCH 2.6.24-rc5-mm 1/3] gpiolib: basic support for 16-bit PCA9539 GPIO expander

[David Brownell]

> +	/* initialize cached registers from their original values */
> +	pca9539_read_reg(chip, PCA9539_OUTPUT, &chip->reg_output);
> +	pca9539_read_reg(chip, PCA9539_DIRECTION, &chip->reg_direction);
> +
> +	/* set platform specific polarity inversion */
> +	pca9539_write_reg(chip, PCA9539_INVERT, pdata->invert);
> +
> +	ret = pca9539_init_gpio(chip);
> +	if (ret)
> +		goto out_failed;

I'm glad to see this patch no longer trashes previous chip state,
but there's still an issue in that area.  Surely the code should

	ret = pca9539_read_reg(...)
	if (ret)
		goto out_failed;

and likewise for the write?  If the chip isn't present (and thus
an I/O error is reported), its probe() should fail.

- Dave

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