linux-kernel - Re: [PATCH v7 2/2] mmc: sdhci-msm: Initial support for MSM chipsets

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Date:	Fri, 06 Dec 2013 14:02:55 +0200
From:	Georgi Djakov <gdjakov@...sol.com>
To:	Mark Rutland <mark.rutland@....com>
CC:	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"cjb@...top.org" <cjb@...top.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	Pawel Moll <Pawel.Moll@....com>,
	"swarren@...dotorg.org" <swarren@...dotorg.org>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	"galak@...eaurora.org" <galak@...eaurora.org>,
	"rob@...dley.net" <rob@...dley.net>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	"subhashj@...eaurora.org" <subhashj@...eaurora.org>
Subject: Re: [PATCH v7 2/2] mmc: sdhci-msm: Initial support for MSM chipsets

On 12/05/2013 12:27 PM, Mark Rutland wrote:
> On Wed, Nov 06, 2013 at 03:56:45PM +0000, Georgi Djakov wrote:
>> This platform driver adds the initial support of Secure
>> Digital Host Controller Interface compliant controller
>> found in Qualcomm MSM chipsets.
>>
>> Signed-off-by: Georgi Djakov <gdjakov@...sol.com>
>> ---
>>   drivers/mmc/host/Kconfig     |   13 +
>>   drivers/mmc/host/Makefile    |    1 +
>>   drivers/mmc/host/sdhci-msm.c |  651 ++++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 665 insertions(+)
>>   create mode 100644 drivers/mmc/host/sdhci-msm.c
>
> [...]
>
>> +static int sdhci_msm_dt_parse_vreg_info(struct device *dev,
>> +                                       struct sdhci_msm_reg_data *vreg,
>> +                                       const char *vreg_name)
>> +{
>> +       int len;
>> +       const __be32 *prop;
>
> Seeing raw property handling in drivers worries me. If there's a reason
> to touch the raw DTB we should add helpers to do it rather than leaking
> binary format issues into drivers.
>
>> +       char prop_name[MAX_PROP_SIZE];
>> +       struct device_node *np = dev->of_node;
>> +
>> +       snprintf(prop_name, MAX_PROP_SIZE, "%s-supply", vreg_name);
>> +       if (!of_parse_phandle(np, prop_name, 0)) {
>> +               dev_info(dev, "No vreg data found for %s\n", vreg_name);
>> +               return -EINVAL;
>> +       }
>> +
>> +       vreg->name = vreg_name;
>> +
>> +       snprintf(prop_name, MAX_PROP_SIZE, "qcom,%s-lpm-sup", vreg_name);
>> +       if (of_get_property(np, prop_name, NULL))
>> +               vreg->lpm_sup = true;
>> +
>> +       snprintf(prop_name, MAX_PROP_SIZE, "qcom,%s-voltage-level", vreg_name);
>> +       prop = of_get_property(np, prop_name, &len);
>> +       if (!prop || (len != (2 * sizeof(__be32)))) {
>> +               dev_warn(dev, "%s %s property\n",
>> +               prop ? "invalid format" : "no", prop_name);
>> +       } else {
>> +               vreg->low_vol_level = be32_to_cpup(&prop[0]);
>> +               vreg->high_vol_level = be32_to_cpup(&prop[1]);
>> +       }
>
> You can use of_property_read_u32_array here.
>
>> +
>> +       snprintf(prop_name, MAX_PROP_SIZE, "qcom,%s-current-level", vreg_name);
>> +       prop = of_get_property(np, prop_name, &len);
>> +       if (!prop || (len != (2 * sizeof(__be32)))) {
>> +               dev_warn(dev, "%s %s property\n",
>> +                        prop ? "invalid format" : "no", prop_name);
>> +       } else {
>> +               vreg->lpm_uA = be32_to_cpup(&prop[0]);
>> +               vreg->hpm_uA = be32_to_cpup(&prop[1]);
>> +       }
>
> Likewise.
>

I will clean this up use only of_property_read_u32_array() and 
of_property_read_bool() for DT parsing. Thanks!


> [...]
>
>> +       /*
>> +        * CORE_SW_RST above may trigger power irq if previous status of PWRCTL
>> +        * was either BUS_ON or IO_HIGH_V. So before we enable the power irq
>> +        * interrupt in GIC (by registering the interrupt handler), we need to
>> +        * ensure that any pending power irq interrupt status is acknowledged
>> +        * otherwise power irq interrupt handler would be fired prematurely.
>> +        */
>> +       irq_status = readl_relaxed(msm_host->core_mem + CORE_PWRCTL_STATUS);
>> +       writel_relaxed(irq_status, (msm_host->core_mem + CORE_PWRCTL_CLEAR));
>> +       irq_ctl = readl_relaxed(msm_host->core_mem + CORE_PWRCTL_CTL);
>> +       if (irq_status & (CORE_PWRCTL_BUS_ON | CORE_PWRCTL_BUS_OFF))
>> +               irq_ctl |= CORE_PWRCTL_BUS_SUCCESS;
>> +       if (irq_status & (CORE_PWRCTL_IO_HIGH | CORE_PWRCTL_IO_LOW))
>> +               irq_ctl |= CORE_PWRCTL_IO_SUCCESS;
>> +       writel_relaxed(irq_ctl, (msm_host->core_mem + CORE_PWRCTL_CTL));
>> +       /*
>> +        * Ensure that above writes are propogated before interrupt enablement
>> +        * in GIC.
>> +        */
>> +       mb();
>
> Does this guarantee that the device has finished responding to the write
> and deasserted the interrupt line (i.e. does the device only acknowledge
> the write once that is true)?
>

I am not sure that i understand your concern. The write to 
CORE_PWRCTL_CTL should acknowledge and deassert the interrupt.

Thanks,
Georgi
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