linux-kernel - Re: [PATCH v2 04/11] mmc: host: omap_hsmmc: add code for special init of wl1251 to get rid of pandora_wl1251_init

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Message-Id: <607E3AE4-65BF-4003-86BE-C70646D53D09@goldelico.com>
Date:   Wed, 30 Oct 2019 18:24:28 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Benoît Cousson <bcousson@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        Kalle Valo <kvalo@...eaurora.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        David Sterba <dsterba@...e.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Petr Mladek <pmladek@...e.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Yangtao Li <tiny.windzz@...il.com>,
        Alexios Zavras <alexios.zavras@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Allison Randal <allison@...utok.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        John Stultz <john.stultz@...aro.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-omap <linux-omap@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>, kernel@...a-handheld.com,
        "# 4.0+" <stable@...r.kernel.org>
Subject: Re: [PATCH v2 04/11] mmc: host: omap_hsmmc: add code for special init of wl1251 to get rid of pandora_wl1251_init_card

Hi Ulf,

> Am 30.10.2019 um 16:51 schrieb Ulf Hansson <ulf.hansson@...aro.org>:
> 
>> +
>> +               np = of_get_compatible_child(np, "ti,wl1251");
>> +               if (np) {
>> +                       /*
>> +                        * We have TI wl1251 attached to MMC3. Pass this information to
>> +                        * SDIO core because it can't be probed by normal methods.
>> +                        */
>> +
>> +                       dev_info(host->dev, "found wl1251\n");
>> +                       card->quirks |= MMC_QUIRK_NONSTD_SDIO;
>> +                       card->cccr.wide_bus = 1;
>> +                       card->cis.vendor = 0x104c;
>> +                       card->cis.device = 0x9066;
>> +                       card->cis.blksize = 512;
>> +                       card->cis.max_dtr = 24000000;
>> +                       card->ocr = 0x80;
> 
> These things should really be figured out by the mmc core during SDIO
> card initialization itself, not via the host ops ->init_card()
> callback. That is just poor hack, which in the long run should go
> away.

Yes, I agree.

But I am just the poor guy who is trying to fix really broken code with
as low effort as possible.

I don't even have a significant clue what this code is exactly doing and what
the magic values mean. They were setup by pandora_wl1251_init_card() in the
same way so that I have just moved the code here and make it called in (almost)
the same situation.

> Moreover, I think we should add a subnode to the host node in the DT,
> to describe the embedded SDIO card, rather than parsing the subnode
> for the SDIO func - as that seems wrong to me.

You mean a second subnode?

The wl1251 is the child node of the mmc node and describes the SDIO card.
We just check if it is a wl1251 or e.g. wl1837 or something else or even
no child.

> To add a subnode for the SDIO card, we already have a binding that I
> think we should extend. Please have a look at
> Documentation/devicetree/bindings/mmc/mmc-card.txt.
> 
> If you want an example of how to implement this for your case, do a
> git grep "broken-hpi" in the driver/mmc/core/, I think it will tell
> you more of what I have in mind.

So while I agree that it should be improved in the long run, we should
IMHO fix the hack first (broken since v4.9!), even if it remains a hack
for now. Improving this part seems to be quite independent and focussed
on the mmc subsystem, while the other patches involve other subsystems.

Maybe should we make a REVISIT note in the code? Or add something to
the commit message about the idea how it should be done right?

> 
>> +                       of_node_put(np);
>> +               }
>> +       }
>> }
>> 
>> static void omap_hsmmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
>> --
>> 2.19.1
>> 
> 
> Kind regards
> Uffe


BR and thanks,
Nikolaus