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Date:   Mon, 26 Apr 2021 10:49:32 +0200
From:   Johan Hovold <johan@kernel.org>
To:     tu pham <thanhtung1909@gmail.com>
Cc:     gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, Hung.Nguyen@silabs.com,
        Tung.Pham@silabs.com, Pho Tran <pho.tran@silabs.com>
Subject: Re: [PATCH v11] USB: serial: cp210x: Add support for GPIOs on CP2108
Message-ID: <YIZ+nKw6iNcQP26E@hovoldconsulting.com>
References: <20210426084213.9823-1-tupham@silabs.com>
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On Mon, Apr 26, 2021 at 03:42:13PM +0700, tu pham wrote:
> From: Pho Tran <pho.tran@silabs.com>
> 
> Similar to other CP210x devices, GPIO interfaces (gpiochip) should be
> supported for CP2108.
> 
> CP2108 has 4 serial interfaces but only 1 set of GPIO pins are shared
> to all of those interfaces. So, just need to initialize GPIOs of CP2108
> with only one interface (I use interface 0). It means just only 1 gpiochip
> device file will be created for CP2108.
> 
> CP2108 has 16 GPIOs, So data types of several variables need to be is u16
> instead of u8(in struct cp210x_serial_private). This doesn't affect other
> CP210x devices.
> 
> Because CP2108 has 16 GPIO pins, the parameter passed by cp210x functions
> will be different from other CP210x devices. So need to check part number
> of the device to use correct data format  before sending commands to
> devices.
> 
> Like CP2104, CP2108 have GPIO pins with configurable options. Therefore,
> should be mask all pins which are not in GPIO mode in cp2108_gpio_init()
> function.
> 
> Signed-off-by: Pho Tran <pho.tran@silabs.com>
> Co-developed-by: Tung Pham <tung.pham@silabs.com>

You still need to sign-off as mentioned in the document I referred to.

Johan