Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31;
MIME-Version: 1.0
Date:   Fri, 15 Sep 2023 09:25:48 +0200
From:   =?UTF-8?Q?Rafa=C5=82_Mi=C5=82ecki?= <rafal@milecki.pl>
To:     Florian Fainelli <f.fainelli@gmail.com>
Cc:     =?UTF-8?Q?Rafa=C5=82_Mi=C5=82ecki?= <zajec5@gmail.com>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        linux-mtd@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        =?UTF-8?Q?Ar=C4=B1n=C3=A7_=C3=9CNAL?= <arinc.unal@arinc9.com>,
        Florian Fainelli <florian.fainelli@broadcom.com>,
        Scott Branden <scott.branden@broadcom.com>
Subject: Re: [PATCH] nvmem: brcm_nvram: store a copy of NVRAM content
In-Reply-To: <28fad55f-1253-deb2-9615-b32746129664@gmail.com>
References: <20230914064922.3986-1-zajec5@gmail.com>
 <28fad55f-1253-deb2-9615-b32746129664@gmail.com>
User-Agent: Roundcube Webmail/1.4.13
Message-ID: <58a017a92ee82f95972b0a14c604f313@milecki.pl>
Content-Type: text/plain; charset=UTF-8;
 format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 2023-09-14 23:26, Florian Fainelli wrote:
> On 9/13/23 23:49, Rafał Miłecki wrote:
>> From: Rafał Miłecki <rafal@milecki.pl>
>> 
>> This driver uses MMIO access for reading NVRAM from a flash device.
>> Underneath there is a flash controller that reads data and provides
>> mapping window.
>> 
>> Using MMIO interface affects controller configuration and may break 
>> real
>> controller driver. It was reported by multiple users of devices with
>> NVRAM stored on NAND.
>> 
>> Modify driver to read & cache all NVRAM content during init and use 
>> that
>> copy to provide NVMEM data when requested.
>> 
>> Link: 
>> https://lore.kernel.org/linux-mtd/CACna6rwf3_9QVjYcM+847biTX=K0EoWXuXcSMkJO1Vy_5vmVqA@mail.gmail.com/
>> Cc: Arınç ÜNAL <arinc.unal@arinc9.com>
>> Cc: Florian Fainelli <florian.fainelli@broadcom.com>
>> Cc: Scott Branden <scott.branden@broadcom.com>
>> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
>> ---
> [snip]
>> -	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
>> -	if (IS_ERR(priv->base))
>> -		return PTR_ERR(priv->base);
>> +	base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
>> +	if (IS_ERR(base))
>> +		return PTR_ERR(base);
>> +
>> +	priv->size = resource_size(res);
>> +
>> +	priv->data = devm_kzalloc(dev, priv->size, GFP_KERNEL);
> 
> These can conceivably quite big data structures, how about using 
> kvmalloc()?

Good idea.

Actual NVRAM data usually doesn't take much space, but it reserves quite 
a lot and we need all of that to full expose NVMEM device content.

-- 
Rafał Miłecki