linux-kernel - Re: [PATCH 3/4] memory: mtk-smi: mt8188: Add SMI clamp function

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Message-ID: <72c8d4b0bfdce89328ee1c99363441f1a3bbf5b2.camel@mediatek.com>
Date: Fri, 25 Oct 2024 09:33:32 +0000
From: Friday Yang (杨阳) <Friday.Yang@...iatek.com>
To: "robh@...nel.org" <robh@...nel.org>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>, "conor+dt@...nel.org"
	<conor+dt@...nel.org>, "krzk@...nel.org" <krzk@...nel.org>
CC: "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Yong Wu (吴勇) <Yong.Wu@...iatek.com>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 3/4] memory: mtk-smi: mt8188: Add SMI clamp function

On Thu, 2024-10-24 at 13:56 +0200, AngeloGioacchino Del Regno wrote:
> Il 24/10/24 03:29, Friday Yang (杨阳) ha scritto:
> > On Wed, 2024-08-21 at 11:00 +0200, Krzysztof Kozlowski wrote:
> > >   	
> > > External email : Please do not click links or open attachments
> > > until
> > > you have verified the sender or the content.
> > >   On 21/08/2024 10:26, friday.yang wrote:
> > > > In order to avoid handling glitch signal when MTCMOS on/off,
> > > > SMI
> > > 
> > > need
> > > > clamp and reset operation. Parse power reset settings for LARBs
> > > 
> > > which
> > > > need to reset. Register genpd callback for SMI LARBs and apply
> > > 
> > > reset
> > > > operations in the callback.
> > > > 
> > > > Signed-off-by: friday.yang <friday.yang@...iatek.com>
> > > > ---
> > > >   drivers/memory/mtk-smi.c | 148
> > > 
> > > ++++++++++++++++++++++++++++++++++++++-
> > > >   1 file changed, 146 insertions(+), 2 deletions(-)
> > > > 
> > > 
> > > ...
> > > 
> > > > +
> > > > +static int mtk_smi_larb_parse_reset_info(struct mtk_smi_larb
> > > 
> > > *larb)
> > > > +{
> > > > +struct device_node *reset_node;
> > > > +struct device *dev = larb->dev;
> > > > +int ret;
> > > > +
> > > > +/* only larb with "resets" need to get reset setting */
> > > > +reset_node = of_parse_phandle(dev->of_node, "resets", 0);
> > > 
> > > Nope, you do not parse rasets.
> > 
> > 1.If I need to use the Linux reset control framework, 'resets' is
> > the
> > required property.
> 
> Leave that to the reset API, don't manually parse the resets phandle
> here,
> that's what Krzysztof was meaning.

OK, I will just use 'larb->rst_con' to judge whether this larb need
reset or not, not parse 'resets' here.

> 
> > 2.'reset-names' give the list of reset signal name strings sorted
> > in
> > the same order as the 'resets' property. SMI driver will use
> > 'reset-
> > names' to match reset signal names with reset specifiers.
> > 3.Not all SMI larbs need to apply reset operations, only SMI larbs
> > which may have bus glitch issues need this. Just to confirm if this
> > larb support reset function.
> > 
> > > 
> > > > +if (!reset_node)
> > > > +return 0;
> > > > +of_node_put(reset_node);
> > > > +
> > > > +larb->rst_con = devm_reset_control_get(dev, "larb_rst");
> 
> "larb" is just fine as a name: it's clear that this is a reset, as
> it's specified as `reset-names = "name"`.

Thanks, I will fix it to 'larb'.

> 
> > > 
> > > Where are the bindings? Why do you add undocumented properties?
> > > How
> > > possible this passes dtbs_check???
> > > 
> > 
> > This is not the new added property in SMI larb DT node.
> > It is the reset signal name which is inclued in 'reset-names'.
> > Just like this:
> > 
> > resets = <&imgsys1_dip_nr_rst MT8188_SIM_RST_LARB15>;
> > reset-name = 'larb_rst';
> > 
> > Maybe I can add this name to the 'reset-name' property binding
> > description, like this, is this clear for you?
> > 
> > reset-name:
> 
> It's "reset-names" btw.

Yes, you are right.

> 
> >      const: larb_rst
> >      description: the name of reset signal. SMI driver need to
> > obtain 		
> >   the reset controller based on this.
> > 
> > > 
> > > > +if (IS_ERR(larb->rst_con))
> > > > +return dev_err_probe(dev, PTR_ERR(larb->rst_con),
> > > > +     "cannot get larb reset controller\n");
> > > > +
> > > > +larb->nb.notifier_call = mtk_smi_genpd_callback;
> > > > +ret = dev_pm_genpd_add_notifier(dev, &larb->nb);
> > > > +if (ret) {
> > > > +dev_err(dev, "Failed to add genpd callback %d\n", ret);
> > > > +return -EINVAL;
> > > > +}
> > > > +
> > > > +return 0;
> > > > +}
> > > > +
> > > >   static int mtk_smi_larb_probe(struct platform_device *pdev)
> > > >   {
> > > >   struct mtk_smi_larb *larb;
> > > > @@ -538,6 +662,7 @@ static int mtk_smi_larb_probe(struct
> > > 
> > > platform_device *pdev)
> > > >   if (!larb)
> > > >   return -ENOMEM;
> > > >   
> > > > +larb->dev = dev;
> > > >   larb->larb_gen = of_device_get_match_data(dev);
> > > >   larb->base = devm_platform_ioremap_resource(pdev, 0);
> > > >   if (IS_ERR(larb->base))
> > > > @@ -554,15 +679,29 @@ static int mtk_smi_larb_probe(struct
> > > 
> > > platform_device *pdev)
> > > >   if (ret < 0)
> > > >   return ret;
> > > >   
> > > > -pm_runtime_enable(dev);
> > > > +/* find sub common to clamp larb for ISP software reset */
> > > > +ret = mtk_smi_larb_parse_clamp_info(larb);
> > > > +if (ret) {
> > > > +dev_err(dev, "Failed to get clamp setting for larb\n");
> > > > +goto err_pm_disable;
> > > > +}
> > > > +
> > > > +ret = mtk_smi_larb_parse_reset_info(larb);
> > > > +if (ret) {
> > > > +dev_err(dev, "Failed to get power setting for larb\n");
> > > > +goto err_pm_disable;
> > > > +}
> > > > +
> > > >   platform_set_drvdata(pdev, larb);
> > > >   ret = component_add(dev, &mtk_smi_larb_component_ops);
> > > >   if (ret)
> > > >   goto err_pm_disable;
> > > > +
> > > > +pm_runtime_enable(dev);
> > > > +
> > > >   return 0;
> > > >   
> > > >   err_pm_disable:
> > > > -pm_runtime_disable(dev);
> > > >   device_link_remove(dev, larb->smi_common_dev);
> > > 
> > > Label asls pm disable. Where is the pm disable?
> > > 
> > 
> > Thanks, I will fix it to 'err_link_remove'.
> > 
> 
> ...or you can just use devm_pm_runtime_enable() instead, and not
> worry
> about disabling it on your own.
> 

This is a good choice, but in this smi clamp patchset, I will just
modify the label as 'err_link_remove'.

> Regards,
> Angelo