[PATCH] mmc: sdhci-xenon: Fix clock resource by adding an optional bus clock
Ziji Hu
davidhuzj at gmail.com
Fri Sep 29 19:47:39 PDT 2017
Hi Gregory,
2017-09-28 23:05 GMT+08:00 Gregory CLEMENT <gregory.clement at free-electrons.com>:
> On Armada 7K/8K we need to explicitly enable the bus clock. The bus clock
> is optional because not all the SoCs need them but at least for Armada
> 7K/8K it is actually mandatory.
>
> The binding documentation is updating accordingly.
>
> Without this patch the kernel hand during boot if the mvpp2.2 network
> driver was not present in the kernel. Indeed the clock needed by the
> xenon controller was set by the network driver.
>
> Fixes: 3a3748dba881 ("mmc: sdhci-xenon: Add Marvell Xenon SDHC core
> functionality)"
> CC: Stable <stable at vger.kernel.org>
> Signed-off-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
> ---
> Hi Ulf and Adrian,
>
> This patch should be merged in 4.14-rc, as it fixes real issues.
>
> This patch maye looks like just as a nice clean-up but it is not. On
> the earlier version of the series adding the support for the xenon
> controller there was already this axi bus clock. But at this moment
> the documentation for the clock on the Armada 7K/8K was missing and
> there was no driver for it, so we just use the clock set by the
> bootloader and never change them that's why it worked without any
> visible problem.
>
> Then as explained in the commit log the network driver enabled the
> clock for us, and it happened that it was setup before the xenon
> driver. It is only thanks the new information we received on the
> clocks of the Sov and with more exhaustive testes that we found this
> issue and the fix for it.
I know very little about clk in Linux.
But I just happened to review this very issue before I left Marvell.
I had some concerns about this patch at that time.
Please check the following.
1. If that network device is used again, so that clock will be setup *twice*
since there are two duplicated clock setup in that network driver
and Xenon driver. Right?
2. If that network device is used again and Xenon later exists and
shutdown the clock,
will that network device be corrupted?
3. In my very own opinion, such a shared AXI bus clock might be
controlled in u-boot or
a "SoC-level" init routine.
Please correct me if there is any misunderstanding.
Thank you.
Best regards,
Hu Ziji
>
> Thanks,
>
> Gregory
>
>
> .../bindings/mmc/marvell,xenon-sdhci.txt | 12 ++++++-----
> drivers/mmc/host/sdhci-xenon.c | 25 +++++++++++++++++++---
> drivers/mmc/host/sdhci-xenon.h | 1 +
> 3 files changed, 30 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt b/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
> index b878a1e305af..6f3db1f809ab 100644
> --- a/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
> +++ b/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
> @@ -16,11 +16,13 @@ Required Properties:
>
> - clocks:
> Array of clocks required for SDHC.
> - Require at least input clock for Xenon IP core.
> + Require at least input clock for Xenon IP core. For Armada AP806 and
> + CP110, the AXI clock is also mandatory.
>
> - clock-names:
> Array of names corresponding to clocks property.
> The input clock for Xenon IP core should be named as "core".
> + The input clock for the AXI bus must be named as "axi".
>
> - reg:
> * For "marvell,armada-3700-sdhci", two register areas.
> @@ -106,8 +108,8 @@ Example:
> compatible = "marvell,armada-ap806-sdhci";
> reg = <0xaa0000 0x1000>;
> interrupts = <GIC_SPI 13 IRQ_TYPE_LEVEL_HIGH>
> - clocks = <&emmc_clk>;
> - clock-names = "core";
> + clocks = <&emmc_clk>,<&axi_clk>;
> + clock-names = "core","axi";
> bus-width = <4>;
> marvell,xenon-phy-slow-mode;
> marvell,xenon-tun-count = <11>;
> @@ -126,8 +128,8 @@ Example:
> interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>
> vqmmc-supply = <&sd_vqmmc_regulator>;
> vmmc-supply = <&sd_vmmc_regulator>;
> - clocks = <&sdclk>;
> - clock-names = "core";
> + clocks = <&sdclk>,<&axi_clk>;
> + clock-names = "core","axi";
> bus-width = <4>;
> marvell,xenon-tun-count = <9>;
> };
> diff --git a/drivers/mmc/host/sdhci-xenon.c b/drivers/mmc/host/sdhci-xenon.c
> index 2eec2e652c53..845575593b59 100644
> --- a/drivers/mmc/host/sdhci-xenon.c
> +++ b/drivers/mmc/host/sdhci-xenon.c
> @@ -466,6 +466,7 @@ static int xenon_probe(struct platform_device *pdev)
> {
> struct sdhci_pltfm_host *pltfm_host;
> struct sdhci_host *host;
> + struct xenon_priv *priv;
> int err;
>
> host = sdhci_pltfm_init(pdev, &sdhci_xenon_pdata,
> @@ -474,6 +475,7 @@ static int xenon_probe(struct platform_device *pdev)
> return PTR_ERR(host);
>
> pltfm_host = sdhci_priv(host);
> + priv = sdhci_pltfm_priv(pltfm_host);
>
> /*
> * Link Xenon specific mmc_host_ops function,
> @@ -491,9 +493,20 @@ static int xenon_probe(struct platform_device *pdev)
> if (err)
> goto free_pltfm;
>
> + priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
> + if (IS_ERR(priv->axi_clk)) {
> + err = PTR_ERR(priv->axi_clk);
> + dev_err(&pdev->dev, "Failed to setup axi clk: %d\n", err);
> + priv->axi_clk = NULL;
> + } else {
> + err = clk_prepare_enable(priv->axi_clk);
> + if (err)
> + goto err_clk;
> + }
> +
> err = mmc_of_parse(host->mmc);
> if (err)
> - goto err_clk;
> + goto err_clk_axi;
>
> sdhci_get_of_property(pdev);
>
> @@ -502,11 +515,11 @@ static int xenon_probe(struct platform_device *pdev)
> /* Xenon specific dt parse */
> err = xenon_probe_dt(pdev);
> if (err)
> - goto err_clk;
> + goto err_clk_axi;
>
> err = xenon_sdhc_prepare(host);
> if (err)
> - goto err_clk;
> + goto err_clk_axi;
>
> pm_runtime_get_noresume(&pdev->dev);
> pm_runtime_set_active(&pdev->dev);
> @@ -527,6 +540,9 @@ static int xenon_probe(struct platform_device *pdev)
> pm_runtime_disable(&pdev->dev);
> pm_runtime_put_noidle(&pdev->dev);
> xenon_sdhc_unprepare(host);
> +err_clk_axi:
> + if (priv->axi_clk)
> + clk_disable_unprepare(priv->axi_clk);
> err_clk:
> clk_disable_unprepare(pltfm_host->clk);
> free_pltfm:
> @@ -538,6 +554,7 @@ static int xenon_remove(struct platform_device *pdev)
> {
> struct sdhci_host *host = platform_get_drvdata(pdev);
> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
>
> pm_runtime_get_sync(&pdev->dev);
> pm_runtime_disable(&pdev->dev);
> @@ -546,6 +563,8 @@ static int xenon_remove(struct platform_device *pdev)
> sdhci_remove_host(host, 0);
>
> xenon_sdhc_unprepare(host);
> + if (priv->axi_clk)
> + clk_disable_unprepare(priv->axi_clk);
>
> clk_disable_unprepare(pltfm_host->clk);
>
> diff --git a/drivers/mmc/host/sdhci-xenon.h b/drivers/mmc/host/sdhci-xenon.h
> index 2bc0510c0769..9994995c7c56 100644
> --- a/drivers/mmc/host/sdhci-xenon.h
> +++ b/drivers/mmc/host/sdhci-xenon.h
> @@ -83,6 +83,7 @@ struct xenon_priv {
> unsigned char bus_width;
> unsigned char timing;
> unsigned int clock;
> + struct clk *axi_clk;
>
> int phy_type;
> /*
> --
> 2.14.1
>
> --
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