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Date:   Fri, 7 May 2021 14:59:18 +0800
From:   Steven Lee <steven_lee@aspeedtech.com>
To:     Andrew Jeffery <andrew@aj.id.au>
CC:     Ulf Hansson <ulf.hansson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Joel Stanley <joel@jms.id.au>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Ryan Chen <ryanchen.aspeed@gmail.com>,
        "moderated list:ASPEED SD/MMC DRIVER" <linux-aspeed@lists.ozlabs.org>,
        "moderated list:ASPEED SD/MMC DRIVER" <openbmc@lists.ozlabs.org>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>,
        Hongwei Zhang <Hongweiz@ami.com>,
        Ryan Chen <ryan_chen@aspeedtech.com>,
        Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
Subject: Re: [PATCH v3 4/5] mmc: sdhci-of-aspeed: Add a helper for updating
 capability register.
Message-ID: <20210507065918.GE23749@aspeedtech.com>
References: <20210506100312.1638-1-steven_lee@aspeedtech.com>
 <20210506100312.1638-5-steven_lee@aspeedtech.com>
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The 05/07/2021 10:13, Andrew Jeffery wrote:
> Hi Steven,
> 
> I have some minor comments. I expect you're going to do a v4 of the 
> series, so if you'd like to clean them up in the process I'd appreciate 
> it.
> 

Yes, I am going to prepare v4 patch for meeting reviewer's expectation
including your comment in this patch.

I've learned a lot from your suggestion for driver upstream.
Many thanks!

> However, from a pragmatic standpoint I think the patch is in good shape.
> 
> On Thu, 6 May 2021, at 19:33, Steven Lee wrote:
> > The patch add a new function aspeed_sdc_set_slot_capability() for
> > updating sdhci capability register.
> 
> The commit message should explain why the patch is necessary and not 
> what it does, as what it does is contained in the diff.
> 
> It's okay to explain *how* the patch acheives its goals if the 
> implementation is subtle or complex.
> 
> Maybe the commit message could be something like:
> 
> 
> ```
> Configure the SDHCIs as specified by the devicetree.
> 
> The hardware provides capability configuration registers for each SDHCI 
> in the global configuration space for the SD controller. Writes to the 
> global capability registers are mirrored to the capability registers in 
> the associated SDHCI. Configuration of the capabilities must be written 
> through the mirror registers prior to initialisation of the SDHCI.
> ```
> 

Thanks for the exmaple, I will modify my commit message.

> > 
> > Signed-off-by: Steven Lee <steven_lee@aspeedtech.com>
> > ---
> >  drivers/mmc/host/sdhci-of-aspeed.c | 57 ++++++++++++++++++++++++++++++
> >  1 file changed, 57 insertions(+)
> > 
> > diff --git a/drivers/mmc/host/sdhci-of-aspeed.c 
> > b/drivers/mmc/host/sdhci-of-aspeed.c
> > index d001c51074a0..4979f98ffb52 100644
> > --- a/drivers/mmc/host/sdhci-of-aspeed.c
> > +++ b/drivers/mmc/host/sdhci-of-aspeed.c
> > @@ -31,6 +31,11 @@
> >  #define   ASPEED_SDC_S0_PHASE_OUT_EN	GENMASK(1, 0)
> >  #define   ASPEED_SDC_PHASE_MAX		31
> >  
> > +/* SDIO{10,20} */
> > +#define ASPEED_SDC_CAP1_1_8V           (0 * 32 + 26)
> > +/* SDIO{14,24} */
> > +#define ASPEED_SDC_CAP2_SDR104         (1 * 32 + 1)
> > +
> >  struct aspeed_sdc {
> >  	struct clk *clk;
> >  	struct resource *res;
> > @@ -70,8 +75,42 @@ struct aspeed_sdhci {
> >  	u32 width_mask;
> >  	struct mmc_clk_phase_map phase_map;
> >  	const struct aspeed_sdhci_phase_desc *phase_desc;
> > +
> >  };
> >  
> > +/*
> > + * The function sets the mirror register for updating
> > + * capbilities of the current slot.
> > + *
> > + *   slot | capability  | caps_reg | mirror_reg
> > + *   -----|-------------|----------|------------
> > + *     0  | CAP1_1_8V   | SDIO140  |   SDIO10
> > + *     0  | CAP2_SDR104 | SDIO144  |   SDIO14
> > + *     1  | CAP1_1_8V   | SDIO240  |   SDIO20
> > + *     1  | CAP2_SDR104 | SDIO244  |   SDIO24
> 
> It would be nice to align the columns to improve readability.
> 

Columns seems are aligned in my mail client(mutt) and my editor(vim).
I paste the above comment in Notepad++, columns are aligned as well.

> > +static void aspeed_sdc_set_slot_capability(struct sdhci_host *host,
> > +					   struct aspeed_sdc *sdc,
> > +					   int capability,
> > +					   bool enable,
> > +					   u8 slot)
> 
> I prefer we don't take up so much vertical space here. I think this 
> could be just a couple of lines with multiple variables per line. We 
> can go to 100 chars per line.
> 

I will change the function as the follows:

static void aspeed_sdc_set_slot_capability(struct sdhci_host *host, struct aspeed_sdc *sdc,
					   int capability, bool enable, u8 slot)

> > +{
> > +	u8 cap_reg;
> > +	u32 mirror_reg_offset, cap_val;
> 
> The rest of the driver follows "reverse christmas tree" (longest to 
> shortest declaration) style, so I prefer we try to maintain consistency 
> where we can. Essentially, declare them in this order:
> 
> u32 mirror_reg_offset;
> u32 cap_val;
> u8 cap_reg;
> 

Will modify it.

> > +
> > +	if (slot > 1)
> > +		return;
> > +
> > +	cap_reg = capability / 32;
> > +	cap_val = sdhci_readl(host, 0x40 + (cap_reg * 4));
> > +	if (enable)
> > +		cap_val |= BIT(capability % 32);
> > +	else
> > +		cap_val &= ~BIT(capability % 32);
> > +	mirror_reg_offset = ((slot + 1) * 0x10) + (cap_reg * 4);
> > +	writel(cap_val, sdc->regs + mirror_reg_offset);
> > +}
> > +
> >  static void aspeed_sdc_configure_8bit_mode(struct aspeed_sdc *sdc,
> >  					   struct aspeed_sdhci *sdhci,
> >  					   bool bus8)
> > @@ -329,6 +368,7 @@ static int aspeed_sdhci_probe(struct platform_device *pdev)
> >  {
> >  	const struct aspeed_sdhci_pdata *aspeed_pdata;
> >  	struct sdhci_pltfm_host *pltfm_host;
> > +	struct device_node *np = pdev->dev.of_node;
> 
> Again here with the reverse-christmas-tree style, so:
> 
> const struct aspeed_sdhci_pdata *aspeed_pdata;
> struct device_node *np = pdev->dev.of_node;
> struct sdhci_pltfm_host *pltfm_host;
> ...
> 

Will modify it.

> >  	struct aspeed_sdhci *dev;
> >  	struct sdhci_host *host;
> >  	struct resource *res;
> > @@ -372,6 +412,23 @@ static int aspeed_sdhci_probe(struct platform_device *pdev)
> >  
> >  	sdhci_get_of_property(pdev);
> >  
> > +	if (of_property_read_bool(np, "mmc-hs200-1_8v") ||
> > +	    of_property_read_bool(np, "sd-uhs-sdr104")) {
> > +		aspeed_sdc_set_slot_capability(host,
> > +					       dev->parent,
> > +					       ASPEED_SDC_CAP1_1_8V,
> > +					       true,
> > +					       slot);
> 
> Again, this would be nicer if we compress it to as few lines as possible.
> 

Will modify the function as follows:

		aspeed_sdc_set_slot_capability(host, dev->parent, ASPEED_SDC_CAP1_1_8V, true, slot);

> > +	}
> > +
> > +	if (of_property_read_bool(np, "sd-uhs-sdr104")) {
> > +		aspeed_sdc_set_slot_capability(host,
> > +					       dev->parent,
> > +					       ASPEED_SDC_CAP2_SDR104,
> > +					       true,
> > +					       slot);
> 
> As above.
> 

Will modify the function as follows:

		aspeed_sdc_set_slot_capability(host, dev->parent, ASPEED_SDC_CAP2_SDR104,
					       true, slot);

> Cheers,
> 
> Andrew