Date:   Tue, 21 Jun 2022 16:11:30 +0300
From:   Tomer Maimon <tmaimon77@...il.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Avi Fishman <avifishman70@...il.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        devicetree <devicetree@...r.kernel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Greg KH <gregkh@...uxfoundation.org>,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        Jiri Slaby <jirislaby@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>,
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        Robert Hancock <robert.hancock@...ian.com>,
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        Patrick Venture <venture@...gle.com>,
        Vinod Koul <vkoul@...nel.org>, Will Deacon <will@...nel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Nancy Yuen <yuenn@...gle.com>
Subject: Re: [PATCH v3 06/18] clk: npcm8xx: add clock controller

Hi Christophe,

On Mon, 20 Jun 2022 at 20:59, Christophe JAILLET
<christophe.jaillet@...adoo.fr> wrote:
>
> Le 20/06/2022 à 14:48, Tomer Maimon a écrit :
> > Hi Christophe,
> >
> > Thanks for your comments.
> >
> > On Sun, 19 Jun 2022 at 20:14, Christophe JAILLET
> > <christophe.jaillet-39ZsbGIQGT5GWvitb5QawA@...lic.gmane.org> wrote:
> >>
> >> Le 19/06/2022 à 17:12, Tomer Maimon a écrit :
> >>> Nuvoton Arbel BMC NPCM8XX contains an integrated clock controller which
> >>> generates and supplies clocks to all modules within the BMC.
> >>>
> >>> Signed-off-by: Tomer Maimon <tmaimon77-Re5JQEeQqe8AvxtiuMwx3w-XMD5yJDbdMQAvxtiuMwx3w@...lic.gmane.organe.org>
> >>> ---
> >>>    drivers/clk/Kconfig       |   6 +
> >>>    drivers/clk/Makefile      |   1 +
> >>>    drivers/clk/clk-npcm8xx.c | 760 ++++++++++++++++++++++++++++++++++++++
> >>>    3 files changed, 767 insertions(+)
> >>>    create mode 100644 drivers/clk/clk-npcm8xx.c
> >>>
> >>
> >> [...]
> >>
> >> Hi, below a few comments related to error handling and possible
> >> dev_err_probe() usage to savec a few LoC.
> >>
> >> CJ
> >>
> >>> +static struct clk_hw *
> >>> +npcm8xx_clk_register_pll(struct device *dev, void __iomem *pllcon,
> >>> +                      const char *name, const char *parent_name,
> >>> +                      unsigned long flags)
> >>> +{
> >>> +     struct npcm8xx_clk_pll *pll;
> >>> +     struct clk_init_data init;
> >>> +     struct clk_hw *hw;
> >>> +     int ret;
> >>> +
> >>> +     pll = kzalloc(sizeof(*pll), GFP_KERNEL);
> >>> +     if (!pll)
> >>> +             return ERR_PTR(-ENOMEM);
> >>> +
> >>> +     pr_debug("%s reg, name=%s, p=%s\n", __func__, name, parent_name);
> >>> +
> >>> +     init.name = name;
> >>> +     init.ops = &npcm8xx_clk_pll_ops;
> >>> +     init.parent_names = &parent_name;
> >>> +     init.num_parents = 1;
> >>> +     init.flags = flags;
> >>> +
> >>> +     pll->pllcon = pllcon;
> >>> +     pll->hw.init = &init;
> >>> +
> >>> +     hw = &pll->hw;
> >>> +
> >>> +     ret = devm_clk_hw_register(dev, hw);
> >>> +     if (ret) {
> >>> +             kfree(pll);
> >>
> >> Hi,
> >>
> >> there is no other kfree(() in this patch. It is handled by the framework
> >> once the clk is registered or should there be another kfree() somewhere
> >> or should pll be devm_alloc()'ed?
> > Could use the devm_kzalloc but the hw is sent to the devm function and
> > not the pll struct.
>
> My point, as explained below is that some resources are managed (i.e.
> allocated by a devm_ function and released by the framework if the probe
> fails or if the driver is removed), but not all.
>
> I think that it is not consistent and that maybe the release of the
> corresponding resources should be handled in a way or another.
Thanks for your clarification will Address in V4
>
> >>
> >>
> >>> +             return ERR_PTR(ret);
> >>> +     }
> >>> +
> >>> +     return hw;
> >>> +}
> >>> +
> >>
> >> [...]
> >>
> >>> +static int npcm8xx_clk_probe(struct platform_device *pdev)
> >>> +{
> >>> +     struct clk_hw_onecell_data *npcm8xx_clk_data;
> >>> +     struct device *dev = &pdev->dev;
> >>> +     void __iomem *clk_base;
> >>> +     struct clk_hw *hw;
> >>> +     int i;
> >>> +
> >>> +     npcm8xx_clk_data = devm_kzalloc(dev, struct_size(npcm8xx_clk_data, hws,
> >>> +                                                      NPCM8XX_NUM_CLOCKS),
> >>> +                                     GFP_KERNEL);
> >>> +     if (!npcm8xx_clk_data)
> >>> +             return -ENOMEM;
> >>> +
> >>> +     clk_base = devm_platform_ioremap_resource(pdev, 0);
> >>> +     if (IS_ERR(clk_base))
> >>> +             return PTR_ERR(clk_base);
> >>> +
> >>> +     npcm8xx_clk_data->num = NPCM8XX_NUM_CLOCKS;
> >>> +
> >>> +     for (i = 0; i < NPCM8XX_NUM_CLOCKS; i++)
> >>> +             npcm8xx_clk_data->hws[i] = ERR_PTR(-EPROBE_DEFER);
> >>> +
> >>> +     /* Reference 25MHz clock */
> >>> +     hw = clk_hw_register_fixed_rate(dev, "refclk", NULL, 0, NPCM8XX_REF_CLK);
> >>
> >> Other resoruces are managed, but not this one.
> >> Is it on purpose?
> > This is the fixed clock - the SoC Reference clock, what do you mean by
> > not managed?
>
> clk_hw_register_fixed_rate() allocates some memory. If an error occures
> later on or if the driver is .remove()'ed, this memory will leak.
> (unless I missed something).
>
> Most of your other function calls use some devm_ variant, so the
> corresponding resources are released automatically in case of error or
> if the driver is unloaed.
Thanks for your clarification will Address in V4
>
> >> Is an error handling path needed or a devm_add_action_or_reset()?
> >>
> >>> +     if (IS_ERR(hw))
> >>> +             return PTR_ERR(hw);
> >>> +     npcm8xx_clk_data->hws[NPCM8XX_CLK_REFCLK] = hw;
> >>> +
> >>> +     /* Register plls */
> >>> +     for (i = 0; i < ARRAY_SIZE(npcm8xx_plls); i++) {
> >>> +             const struct npcm8xx_clk_pll_data *pll_data = &npcm8xx_plls[i];
> >>> +
> >>> +             hw = npcm8xx_clk_register_pll(dev, clk_base + pll_data->reg,
> >>> +                                           pll_data->name,
> >>> +                                           pll_data->parent_name,
> >>> +                                           pll_data->flags);
> >>> +             if (IS_ERR(hw)) {
> >>> +                     dev_err(dev, "npcm8xx_clk: Can't register pll\n");
> >>> +                     return PTR_ERR(hw);
> >>> +             }
> >>> +
> >>> +             if (pll_data->onecell_idx >= 0)
> >>> +                     npcm8xx_clk_data->hws[pll_data->onecell_idx] = hw;
> >>> +     }
> >>> +
> >>> +     /* Register fixed dividers */
> >>> +     hw = devm_clk_hw_register_fixed_factor(dev, NPCM8XX_CLK_S_PLL1_DIV2,
> >>> +                                            NPCM8XX_CLK_S_PLL1, 0, 1, 2);
> >>> +     if (IS_ERR(hw)) {
> >>> +             dev_err(dev, "npcm8xx_clk: Can't register fixed div\n");
> >>> +             return PTR_ERR(hw);
> >>
> >> return dev_err_probe()?
> > it will save online but still enter to a bigger function, I am not
> > sure that the error will be EPROBE_DEFER, and we have returned the
> > error in the code.
>
> It is mostly a matter of taste, so if you don't think my proposal
> improves anything, just forget about it.
>
> >>
> >>> +     }
> >>> +
> >>> +     hw = devm_clk_hw_register_fixed_factor(dev, NPCM8XX_CLK_S_PLL2_DIV2,
> >>> +                                            NPCM8XX_CLK_S_PLL2, 0, 1, 2);
> >>> +     if (IS_ERR(hw)) {
> >>> +             dev_err(dev, "npcm8xx_clk: Can't register pll div2\n");
> >>> +             return PTR_ERR(hw);
> >>
> >> Same here and in other calls below.
> >>
> >>> +     }
> >>> +
> >>> +     hw = devm_clk_hw_register_fixed_factor(dev, NPCM8XX_CLK_S_PRE_CLK,
> >>> +                                            NPCM8XX_CLK_S_CPU_MUX, 0, 1, 2);
> >>> +     if (IS_ERR(hw)) {
> >>> +             dev_err(dev, "npcm8xx_clk: Can't register ckclk div2\n");
> >>> +             return PTR_ERR(hw);
> >>> +     }
> >>> +
> >>> +     hw = devm_clk_hw_register_fixed_factor(dev, NPCM8XX_CLK_S_AXI,
> >>> +                                            NPCM8XX_CLK_S_TH, 0, 1, 2);
> >>> +     if (IS_ERR(hw)) {
> >>> +             dev_err(dev, "npcm8xx_clk: Can't register axi div2\n");
> >>> +             return PTR_ERR(hw);
> >>> +     }
> >>> +
> >>> +     hw = devm_clk_hw_register_fixed_factor(dev, NPCM8XX_CLK_S_ATB,
> >>> +                                            NPCM8XX_CLK_S_AXI, 0, 1, 2);
> >>> +     if (IS_ERR(hw)) {
> >>> +             dev_err(dev, "npcm8xx_clk: Can't register atb div2\n");
> >>> +             return PTR_ERR(hw);
> >>> +     }
> >>> +
> >>> +     /* Register muxes */
> >>> +     for (i = 0; i < ARRAY_SIZE(npcm8xx_muxes); i++) {
> >>> +             const struct npcm8xx_clk_mux_data *mux_data = &npcm8xx_muxes[i];
> >>> +
> >>> +             hw = clk_hw_register_mux_table(dev, mux_data->name,
> >>> +                                            mux_data->parent_names,
> >>> +                                            mux_data->num_parents,
> >>> +                                            mux_data->flags,
> >>> +                                            clk_base + NPCM8XX_CLKSEL,
> >>> +                                            mux_data->shift,
> >>> +                                            mux_data->mask, 0,
> >>> +                                            mux_data->table,
> >>> +                                            &npcm8xx_clk_lock);
> >>> +
> >> Same here. Error handling?
> > what do you mean?
>
> I mean the same as above. clk_hw_register_mux_table() allocates some
> memory. If an error occures later on or if the driver is .remove()'ed,
> this memory will leak. (unless I missed something).
>
> Error handling was not a really good wording. You should read "should
> the resources allocated by this function be released if an error occures
> below"
Thanks for your clarification will Address in V4
>
> >>
> >>> +             if (IS_ERR(hw)) {
> >>> +                     dev_err(dev, "npcm8xx_clk: Can't register mux\n");
> >>> +                     return PTR_ERR(hw);
> >>> +             }
> >>> +
> >>> +             if (mux_data->onecell_idx >= 0)
> >>> +                     npcm8xx_clk_data->hws[mux_data->onecell_idx] = hw;
> >>> +     }
> >>> +
> >>> +     /* Register clock dividers specified in npcm8xx_divs */
> >>> +     for (i = 0; i < ARRAY_SIZE(npcm8xx_divs); i++) {
> >>> +             const struct npcm8xx_clk_div_data *div_data = &npcm8xx_divs[i];
> >>> +
> >>> +             hw = clk_hw_register_divider(dev, div_data->name,
> >>> +                                          div_data->parent_name,
> >>> +                                          div_data->flags,
> >>> +                                          clk_base + div_data->reg,
> >>> +                                          div_data->shift, div_data->width,
> >>> +                                          div_data->clk_divider_flags,
> >>> +                                          &npcm8xx_clk_lock);
> >>
> >> devm_clk_hw_register_divider()?
> > Will do.
>
> Here, the devm_ alternative exist. But my point is the same as above.
> (release of resources in cae of error or if the driver is removed)
>
> >>
> >>> +             if (IS_ERR(hw)) {
> >>> +                     dev_err(dev, "npcm8xx_clk: Can't register div table\n");
> >>> +                     return PTR_ERR(hw);
> >>> +             }
> >>> +
> >>> +             if (div_data->onecell_idx >= 0)
> >>> +                     npcm8xx_clk_data->hws[div_data->onecell_idx] = hw;
> >>> +     }
> >>> +
> >>> +     return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
> >>> +                                        npcm8xx_clk_data);
> >>> +}
> >>> +
> >>> +static const struct of_device_id npcm8xx_clk_dt_ids[] = {
> >>> +     { .compatible = "nuvoton,npcm845-clk", },
> >>> +     { }
> >>> +};
> >>> +MODULE_DEVICE_TABLE(of, npcm8xx_clk_dt_ids);
> >>> +
> >>> +static struct platform_driver npcm8xx_clk_driver = {
> >>> +     .probe  = npcm8xx_clk_probe,
> >>> +     .driver = {
> >>> +             .name = "npcm8xx_clk",
> >>> +             .of_match_table = npcm8xx_clk_dt_ids,
> >>> +     },
> >>> +};
> >>> +
> >>> +static int __init npcm8xx_clk_driver_init(void)
> >>> +{
> >>> +     return platform_driver_register(&npcm8xx_clk_driver);
> >>> +}
> >>> +arch_initcall(npcm8xx_clk_driver_init);
> >>> +
> >>
> >
> > Best regards,
> >
> > Tomer
> >
>

Best regards,

Tomer

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