| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <5974d28426057975e701c4a8454b5a13@milecki.pl>
Date: Wed, 08 Mar 2023 19:12:32 +0100
From: Rafał Miłecki <rafal@...ecki.pl>
To: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: Rafał Miłecki <zajec5@...il.com>,
Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
Hector Martin <marcan@...can.st>,
Sven Peter <sven@...npeter.dev>,
Alyssa Rosenzweig <alyssa@...enzweig.io>,
Shawn Guo <shawnguo@...nel.org>,
Sascha Hauer <s.hauer@...gutronix.de>,
Pengutronix Kernel Team <kernel@...gutronix.de>,
Fabio Estevam <festevam@...il.com>,
NXP Linux Team <linux-imx@....com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Kevin Hilman <khilman@...libre.com>,
Jerome Brunet <jbrunet@...libre.com>,
Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
Claudiu Beznea <claudiu.beznea@...rochip.com>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com>,
Andy Gross <agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
Heiko Stuebner <heiko@...ech.de>,
Orson Zhai <orsonzhai@...il.com>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
Chunyan Zhang <zhang.lyra@...il.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
Vincent Shih <vincent.sunplus@...il.com>,
Chen-Yu Tsai <wens@...e.org>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Samuel Holland <samuel@...lland.org>,
Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Michal Simek <michal.simek@...inx.com>,
Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Evgeniy Polyakov <zbr@...emap.net>,
linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
linux-amlogic@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
linux-rockchip@...ts.infradead.org,
linux-stm32@...md-mailman.stormreply.com,
linux-sunxi@...ts.linux.dev, linux-rtc@...r.kernel.org
Subject: Re: [PATCH V2] nvmem: add explicit config option to read OF fixed
cells
On 2023-03-08 19:06, Miquel Raynal wrote:
> Hi Rafał,
>
> rafal@...ecki.pl wrote on Wed, 08 Mar 2023 17:55:46 +0100:
>
>> On 2023-03-08 17:34, Miquel Raynal wrote:
>> > Hi Rafał,
>> >
>> > zajec5@...il.com wrote on Fri, 24 Feb 2023 08:29:03 +0100:
>> >
>> >> From: Rafał Miłecki <rafal@...ecki.pl>
>> >> >> NVMEM subsystem looks for fixed NVMEM cells (specified in DT) by
>> >> default. This behaviour made sense in early days before adding support
>> >> for dynamic cells.
>> >> >> With every new supported NVMEM device with dynamic cells current
>> >> behaviour becomes non-optimal. It results in unneeded iterating over >> DT
>> >> nodes and may result in false discovery of cells (depending on used DT
>> >> properties).
>> >> >> This behaviour has actually caused a problem already with the MTD
>> >> subsystem. MTD subpartitions were incorrectly treated as NVMEM cells.
>> >
>> > That's true, but I expect this to be really MTD specific.
>> >
>> > A concrete proposal below.
>> >
>> >> Also with upcoming support for NVMEM layouts no new binding or driver
>> >> should support fixed cells defined in device node.
>> >
>> > I'm not sure I agree with this statement. We are not preventing new
>> > binding/driver to use fixed cells, or...? We offer a new way to expose
>> > nvmem cells with another way than "fixed-offset" and "fixed-size" OF
>> > nodes.
>>
>> From what I understood all new NVMEM bindings should have cells
>> defined
>> in the nvmem-layout { } node. That's what I mean by saying they should
>> not be defined in device node (but its "nvmem-layout" instead).
>
> Layouts are just another possibility, either you user the nvmem-cells
> compatible and produce nvmem cells with fixed OF nodes, or you use the
> nvmem-layout container. I don't think all new bindings should have
> cells in layouts. It depends if the content is static or not.
>
>> >> Solve this by modifying drivers for bindings that support specifying
>> >> fixed NVMEM cells in DT. Make them explicitly tell NVMEM subsystem to
>> >> read cells from DT.
>> >> >> It wasn't clear (to me) if rtc and w1 code actually uses fixed cells. >> I
>> >> enabled them to don't risk any breakage.
>> >> >> Signed-off-by: Rafał Miłecki <rafal@...ecki.pl>
>> >> [for drivers/nvmem/meson-{efuse,mx-efuse}.c]
>> >> Acked-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
>> >> ---
>> >> V2: Fix stm32-romem.c typo breaking its compilation
>> >> Pick Martin's Acked-by
>> >> Add paragraph about layouts deprecating use_fixed_of_cells
>> >> ---
>> >> drivers/mtd/mtdcore.c | 2 ++
>> >> drivers/nvmem/apple-efuses.c | 1 +
>> >> drivers/nvmem/core.c | 8 +++++---
>> >> drivers/nvmem/imx-ocotp-scu.c | 1 +
>> >> drivers/nvmem/imx-ocotp.c | 1 +
>> >> drivers/nvmem/meson-efuse.c | 1 +
>> >> drivers/nvmem/meson-mx-efuse.c | 1 +
>> >> drivers/nvmem/microchip-otpc.c | 1 +
>> >> drivers/nvmem/mtk-efuse.c | 1 +
>> >> drivers/nvmem/qcom-spmi-sdam.c | 1 +
>> >> drivers/nvmem/qfprom.c | 1 +
>> >> drivers/nvmem/rave-sp-eeprom.c | 1 +
>> >> drivers/nvmem/rockchip-efuse.c | 1 +
>> >> drivers/nvmem/sc27xx-efuse.c | 1 +
>> >> drivers/nvmem/sprd-efuse.c | 1 +
>> >> drivers/nvmem/stm32-romem.c | 1 +
>> >> drivers/nvmem/sunplus-ocotp.c | 1 +
>> >> drivers/nvmem/sunxi_sid.c | 1 +
>> >> drivers/nvmem/uniphier-efuse.c | 1 +
>> >> drivers/nvmem/zynqmp_nvmem.c | 1 +
>> >> drivers/rtc/nvmem.c | 1 +
>> >> drivers/w1/slaves/w1_ds250x.c | 1 +
>> >> include/linux/nvmem-provider.h | 2 ++
>> >> 23 files changed, 29 insertions(+), 3 deletions(-)
>> >> >> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
>> >> index 0feacb9fbdac..1bb479c0f758 100644
>> >> --- a/drivers/mtd/mtdcore.c
>> >> +++ b/drivers/mtd/mtdcore.c
>> >> @@ -523,6 +523,7 @@ static int mtd_nvmem_add(struct mtd_info *mtd)
>> >> config.dev = &mtd->dev;
>> >> config.name = dev_name(&mtd->dev);
>> >> config.owner = THIS_MODULE;
>> >> + config.use_fixed_of_cells = of_device_is_compatible(node, >> "nvmem-cells");
>> >
>> > I am wondering how mtd specific this is? For me all OF nodes containing
>> > the nvmem-cells compatible should be treated as cells providers and
>> > populate nvmem cells as for each children.
>> >
>> > Why don't we just check for this compatible to be present? in
>> > nvmem_add_cells_from_of() ? And if not we just skip the operation.
>> >
>> > This way we still follow the bindings (even though using nvmem-cells in
>> > the compatible property to require cells population was a mistake in
>> > the first place, as discussed in the devlink thread recently) but there
>> > is no need for a per-driver config option?
>>
>> This isn't mtd specific. Please check this patch for all occurrences
>> of
>> the:
>> use_fixed_of_cells = true
>>
>> The very first one: drivers/nvmem/apple-efuses.c driver for the
>> "apple,efuses" binding. That binding supports fixed OF cells, see:
>> Documentation/devicetree/bindings/nvmem/apple,efuses.yaml
>
> I'm saying: based on what has been enforced so far, I would expect all
> fixed cell providers to come with nvmem-cells as compatible, no?
>
> If that's the case we could use that as a common denominator?
Sorry, I don't get it. Have you checked
Documentation/devicetree/bindings/nvmem/apple,efuses.yaml
?
It's a NVMEM provied binding with fixed cells that doesn't use
nvmem-cells as compatible. There are many more.
Powered by blists - more mailing lists