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SubjectRe: [RFC] mmc: cqhci: clear pending interrupt and halt
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On 16/04/19 10:27 AM, Peng Fan wrote:
> Hi Adrian,
>
>>
>> On 16/04/19 9:48 AM, Peng Fan wrote:
>>> On i.MX8MM, we are running Dual Linux OS, with 1st Linux using SD Card
>>> as rootfs storage, 2nd Linux using eMMC as rootfs storage. We let the
>>> the 1st linux configure power/clock for the 2nd Linux.
>>>
>>> When the 2nd Linux is booting into rootfs stage, we let the 1st Linux
>>> to destroy the 2nd linux, then restart the 1st linux, we met SDHCI
>>> dump as following, after we clear the pending interrupt and halt
>>> CQCTL, issue gone.
>>
>> I think it is better if the vendor driver does any necessary resets before
>> initialization.
>
> In drivers/mmc/host/sdhci-esdhc-imx.c, there is a call to cqhci_init
> " 1525 err = cqhci_init(cq_host, host->mmc, false);"
>
> You mean I put the following piece code into sdhci-esdhc-imx.c?
>
> "
> status = cqhci_readl(cq_host, CQHCI_IS);
> cqhci_writel(cq_host, status, CQHCI_IS);
> cqhci_writel(cq_host, CQHCI_HALT, CQHCI_CTL);
> "
>
> How about the following patch?
>
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
> index b8e11a77e274..f2e46ddf9695 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -1435,6 +1435,7 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
> struct cqhci_host *cq_host;
> int err;
> struct pltfm_imx_data *imx_data;
> + u32 status;
>
> host = sdhci_pltfm_init(pdev, &sdhci_esdhc_imx_pdata,
> sizeof(*imx_data));
> @@ -1542,6 +1543,11 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
> err = cqhci_init(cq_host, host->mmc, false);
> if (err)
> goto disable_ahb_clk;
> +
> + status = cqhci_readl(cq_host, CQHCI_IS);
> + cqhci_writel(cq_host, status, CQHCI_IS);
> + cqhci_writel(cq_host, CQHCI_HALT, CQHCI_CTL);
> +
> }
>

It would be nicer to:
1. Define how CQHCI gets reset. For example, with our controllers
SDHCI_RESET_ALL also resets CQHCI.
2. Define when CQHCI should be reset. e.g. using the ->reset() host op for
example.
3. Implement a patch that meets those requirements.

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