linux-kernel - Re: [PATCH 2/2 v16] drm/bridge: Add I2C based driver for ps8640 bridge

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Message-ID: <CAGS+omDsDS5tx=+Efq8LWNd3-asU4r2h=-AE6vdKgfG-p6vdAA@mail.gmail.com>
Date:	Wed, 29 Jun 2016 12:31:23 +0800
From:	Daniel Kurtz <djkurtz@...omium.org>
To:	Emil Velikov <emil.l.velikov@...il.com>
Cc:	Jitao Shi <jitao.shi@...iatek.com>,
	Mark Rutland <mark.rutland@....com>, stonea168@....com,
	ML dri-devel <dri-devel@...ts.freedesktop.org>,
	Ajay Kumar <ajaykumar.rs@...sung.com>,
	Vincent Palatin <vpalatin@...omium.org>,
	cawa cheng <cawa.cheng@...iatek.com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Thierry Reding <treding@...dia.com>,
	devicetree <devicetree@...r.kernel.org>,
	Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@...ts.infradead.org>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Eddie Huang (黃智傑) 
	<eddie.huang@...iatek.com>,
	LAKML <linux-arm-kernel@...ts.infradead.org>,
	Rahul Sharma <rahul.sharma@...sung.com>,
	srv_heupstream <srv_heupstream@...iatek.com>,
	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	Kumar Gala <galak@...eaurora.org>,
	Andy Yan <andy.yan@...k-chips.com>
Subject: Re: [PATCH 2/2 v16] drm/bridge: Add I2C based driver for ps8640 bridge

Hi Emil,

One answer inline below.  The rest I leave to Jitao...

[snip...]

On Fri, Jun 17, 2016 at 3:14 AM, Emil Velikov <emil.l.velikov@...il.com> wrote:

>> +static ssize_t ps8640_update_fw_store(struct device *dev,
>> +                                     struct device_attribute *attr,
>> +                                     const char *buf, size_t count)
>> +{
>> +       struct i2c_client *client = to_i2c_client(dev);
>> +       struct ps8640 *ps_bridge = i2c_get_clientdata(client);
>> +       const struct firmware *fw;
>> +       int error;
>> +
>> +       error = request_firmware(&fw, PS_FW_NAME, dev);
> Can the device operate without a firmware ? If not, why is the
> firmware loaded so later/after user interaction (via sysfs) ? I don't
> recall any other driver in DRM to use such an approach.

The PS8640 has internal flash, so it should always already have a
working firmware.
This sysfs interface is useful for user space initiated field firmware updates.

Regards,
-Daniel

> Regards,
> Emil
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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