Re: [PATCH 6/6] mmc: host: sdhci-sprd: added Spreadtrum's host controller R11

[Chunyan Zhang]

Hi Ulf,

On 11 June 2018 at 15:15, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> On 8 June 2018 at 10:18, Chunyan Zhang <zhang.chunyan@xxxxxxxxxx> wrote:
>> From: Chunyan Zhang <chunyan.zhang@xxxxxxxxxxxxxx>
>>
>> This patch adds the initial support of Secure Digital Host Controller
>> Interface compliant controller - R11 found in some latest Spreadtrum
>> chipsets.
>>
>> R11 is a variant based on SD v4.0 specification.
>>
>> With this driver, mmc can be initialized, can be mounted, read and
>> written.
>>
>> Original-by: Billows Wu <billows.wu@xxxxxxxxxxxxxx>
>> Signed-off-by: Chunyan Zhang <chunyan.zhang@xxxxxxxxxxxxxx>
>> ---
>>  drivers/mmc/host/Kconfig          |  13 ++
>>  drivers/mmc/host/Makefile         |   1 +
>>  drivers/mmc/host/sdhci-sprd-r11.c | 472 ++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 486 insertions(+)
>>  create mode 100644 drivers/mmc/host/sdhci-sprd-r11.c
>
> This is a DT based driver. Please add a separate patch describing the
> corresponding bindings and compatibles.

Ok.

>
> [...]
>
>> +static int sdhci_sprd_get_dt_resource(struct platform_device *pdev,
>> +               struct sdhci_sprd_host *sprd_host)
>> +{
>> +       int ret = 0;
>> +       struct clk *clk;
>> +
>> +       clk = devm_clk_get(&pdev->dev, "sdio");
>> +       if (IS_ERR(clk)) {
>> +               ret = PTR_ERR(clk);
>> +               dev_warn(&pdev->dev, "Failed to get sdio clock (%d)\n", ret);
>> +               goto out;
>> +       }
>> +       sprd_host->clk_sdio = clk;
>> +
>> +       clk = devm_clk_get(&pdev->dev, "source");
>> +       if (IS_ERR(clk)) {
>> +               ret = PTR_ERR(clk);
>> +               dev_warn(&pdev->dev, "Failed to get source clock (%d)\n", ret);
>> +               goto out;
>> +       }
>> +       sprd_host->clk_source = clk;
>> +
>> +       clk_set_parent(sprd_host->clk_sdio, sprd_host->clk_source);
>> +       sprd_host->base_rate = clk_get_rate(sprd_host->clk_source);
>> +       if (!sprd_host->base_rate) {
>> +               sprd_host->base_rate = 26000000;
>> +               dev_warn(&pdev->dev, "The source clock rate is 0\n");
>> +       }
>> +
>
> The above can be managed by the assigned-clock* DT bindings. Please
> have a look at:
>

Ah, didn't notice these bindings, managing in this way is indeed better.

> Documentation/devicetree/bindings/clock/clock-bindings.txt
> drivers/clk/clk-conf.c
>
>> +       clk = devm_clk_get(&pdev->dev, "enable");
>> +       if (IS_ERR(clk)) {
>> +               ret = PTR_ERR(clk);
>> +               dev_warn(&pdev->dev, "Failed to get gate clock (%d)\n", ret);
>
> The printed name of the clock doesn't match the name used in
> devm_clk_get() call.
>
> BTW, I think devm_clk_get() already prints some information when it
> fails to lookup a clock. Isn't that sufficient?

Right, will remove this print.

>
>> +               goto out;
>> +       }
>> +       sprd_host->clk_enable = clk;
>> +
>> +out:
>> +       return ret;
>> +}
>> +
>> +static void sdhci_sprd_set_mmc_struct(struct platform_device *pdev,
>> +                               struct mmc_host *mmc)
>> +{
>> +       struct device_node *np = pdev->dev.of_node;
>> +       struct sdhci_host *host = mmc_priv(mmc);
>> +
>> +       mmc->caps = MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED |
>> +               MMC_CAP_ERASE | MMC_CAP_CMD23;
>> +
>> +       mmc_of_parse(mmc);
>> +       mmc_of_parse_voltage(np, &host->ocr_mask);
>
> mmc_of_parse_voltage() is intended to be used for controllers that
> internally manages the powered to the card. Is that really the case?

I guess it is not, will remove this,

>
> I assume you have external regulator(s) to manage that, no?
>
>> +
>> +       mmc->ocr_avail = 0x40000;
>> +       mmc->ocr_avail_sdio = mmc->ocr_avail;
>> +       mmc->ocr_avail_sd = mmc->ocr_avail;
>> +       mmc->ocr_avail_mmc = mmc->ocr_avail;
>

and this,

> If there is external regulators used, all the above can go away. In
> either case, at least the *_sdio, *_sd, *_mmc can go away.
>
>> +
>> +       mmc->max_current_330 = SDHCI_SPRD_MAX_CUR;
>> +       mmc->max_current_300 = SDHCI_SPRD_MAX_CUR;
>> +       mmc->max_current_180 = SDHCI_SPRD_MAX_CUR;
>

also this :)

> This should probably also be fetched used an external regulator and
> sdhci already manages that.
>
>> +
>> +       host->dma_mask = DMA_BIT_MASK(64);
>> +       mmc_dev(host->mmc)->dma_mask = &host->dma_mask;
>> +}
>
> [...]
>
>> +
>> +static unsigned int sdhci_sprd_get_min_clock(struct sdhci_host *host)
>> +{
>> +       return 400000;
>> +}
>
> Isn't there a more straightforward way to assign the minimum clock
> rate? Do you really need to use a callback?
>

Do you mean setting mmc->f_min directly after sdhci_add_host()?
We would get a different f_min without this callback, since
SDHCI_CLOCK_MUL_MASK in caps1 register is reserved.

>> +
>> +static void sdhci_sprd_reset(struct sdhci_host *host, u8 mask)
>> +{
>> +       sdhci_reset(host, mask);
>> +}
>
> Looks like an unnecessary wrapper function.

Ok, will take out of this wrapper.

>
> [...]
>
>> +static int sdhci_sprd_probe(struct platform_device *pdev)
>> +{
>> +       struct sdhci_host *host;
>> +       struct sdhci_sprd_host *sprd_host;
>> +       int ret = 0;
>> +
>> +       host = sdhci_pltfm_init(pdev, &sdhci_sprd_pdata, sizeof(*sprd_host));
>> +       if (IS_ERR(host))
>> +               return PTR_ERR(host);
>> +
>> +       sprd_host = TO_SPRD_HOST(host);
>> +
>> +       ret = sdhci_sprd_get_dt_resource(pdev, sprd_host);
>> +       if (ret)
>> +               goto pltfm_free;
>> +
>> +       clk_prepare_enable(sprd_host->clk_sdio);
>> +       clk_prepare_enable(sprd_host->clk_enable);
>> +
>> +       sdhci_sprd_init_config(host);
>> +
>> +       sdhci_sprd_set_mmc_struct(pdev, host->mmc);
>> +
>> +       host->version = sdhci_readw(host, SDHCI_HOST_VERSION);
>> +       sprd_host->version = ((host->version & SDHCI_VENDOR_VER_MASK) >>
>> +                              SDHCI_VENDOR_VER_SHIFT);
>> +
>> +       pm_runtime_get_noresume(&pdev->dev);
>> +       pm_runtime_set_active(&pdev->dev);
>> +       pm_runtime_enable(&pdev->dev);
>> +       pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
>> +       pm_runtime_use_autosuspend(&pdev->dev);
>> +       pm_suspend_ignore_children(&pdev->dev, 1);
>> +
>> +       ret = sdhci_add_host(host);
>> +       if (ret) {
>> +               dev_err(&pdev->dev, "failed to add mmc host: %d\n", ret);
>> +               goto pm_runtime_disable;
>> +       }
>> +
>
> Looks like there is a missing call to pm_runtime_put() here, no?
>

Yes, will add back.

> Unless it's intentional to prevent runtime suspend, for whatever reasons!?
>
>> +       return 0;
>> +
>> +pm_runtime_disable:
>> +       pm_runtime_disable(&pdev->dev);
>> +       pm_runtime_set_suspended(&pdev->dev);
>> +
>> +       clk_disable_unprepare(sprd_host->clk_sdio);
>> +       clk_disable_unprepare(sprd_host->clk_enable);
>> +
>> +pltfm_free:
>> +       sdhci_pltfm_free(pdev);
>> +       return ret;
>> +}
>> +
>> +static int sdhci_sprd_remove(struct platform_device *pdev)
>> +{
>> +       struct sdhci_host *host = platform_get_drvdata(pdev);
>> +       struct sdhci_sprd_host *sprd_host = TO_SPRD_HOST(host);
>> +       struct mmc_host *mmc = host->mmc;
>> +
>> +       mmc_remove_host(mmc);
>> +       clk_disable_unprepare(sprd_host->clk_sdio);
>> +       clk_disable_unprepare(sprd_host->clk_enable);
>> +
>> +       mmc_free_host(mmc);
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct of_device_id sdhci_sprd_of_match[] = {
>> +       { .compatible = "sprd,sdhc-r11", },
>
> As stated, don't forget to document this.

Ok.

Thanks for your comments,
Chunyan

>
> [...]
>
> Kind regards
> Uffe