Messages in this thread Patch in this message | | | Date | Wed, 08 Mar 2023 17:55:46 +0100 | From | Rafał Miłecki <> | Subject | Re: [PATCH V2] nvmem: add explicit config option to read OF fixed cells |
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On 2023-03-08 17:34, Miquel Raynal wrote: > Hi Rafał, > > zajec5@gmail.com wrote on Fri, 24 Feb 2023 08:29:03 +0100: > >> From: Rafał Miłecki <rafal@milecki.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).
>> 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@milecki.pl> >> [for drivers/nvmem/meson-{efuse,mx-efuse}.c] >> Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.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
>> config.reg_read = mtd_nvmem_reg_read; >> config.size = mtd->size; >> config.word_size = 1; >> @@ -891,6 +892,7 @@ static struct nvmem_device >> *mtd_otp_nvmem_register(struct mtd_info *mtd, >> config.name = kasprintf(GFP_KERNEL, "%s-%s", dev_name(&mtd->dev), >> compatible); >> config.id = NVMEM_DEVID_NONE; >> config.owner = THIS_MODULE; >> + config.use_fixed_of_cells = true; >> config.type = NVMEM_TYPE_OTP; >> config.root_only = true; >> config.ignore_wp = true; >> diff --git a/drivers/nvmem/apple-efuses.c >> b/drivers/nvmem/apple-efuses.c >> index 9b7c87102104..0119bac43b2c 100644 >> --- a/drivers/nvmem/apple-efuses.c >> +++ b/drivers/nvmem/apple-efuses.c >> @@ -36,6 +36,7 @@ static int apple_efuses_probe(struct platform_device >> *pdev) >> struct resource *res; >> struct nvmem_config config = { >> .dev = &pdev->dev, >> + .use_fixed_of_cells = true, >> .read_only = true, >> .reg_read = apple_efuses_read, >> .stride = sizeof(u32), >> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c >> index 174ef3574e07..6783cd8478d7 100644 >> --- a/drivers/nvmem/core.c >> +++ b/drivers/nvmem/core.c >> @@ -844,9 +844,11 @@ struct nvmem_device *nvmem_register(const struct >> nvmem_config *config) >> if (rval) >> goto err_remove_cells; >> >> - rval = nvmem_add_cells_from_of(nvmem); >> - if (rval) >> - goto err_remove_cells; >> + if (config->use_fixed_of_cells) { >> + rval = nvmem_add_cells_from_of(nvmem); >> + if (rval) >> + goto err_remove_cells; >> + } >> >> dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); >> > > Thanks, > Miquèl
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