linux-kernel - Re: [PATCH V4] mmc: sdhci-msm: Reset GCC_SDCC

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Date:   Tue, 19 Apr 2022 11:46:50 +0530
From:   "Sajida Bhanu (Temp)" <quic_c_sbhanu@...cinc.com>
To:     Philipp Zabel <p.zabel@...gutronix.de>, <adrian.hunter@...el.com>,
        <agross@...nel.org>, <bjorn.andersson@...aro.org>,
        <ulf.hansson@...aro.org>, <chris@...ntf.net>,
        <venkatg@...eaurora.org>, <gdjakov@...sol.com>,
        <quic_asutoshd@...cinc.com>
CC:     <linux-mmc@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_rampraka@...cinc.com>,
        <quic_pragalla@...cinc.com>, <quic_sartgarg@...cinc.com>,
        <quic_nitirawa@...cinc.com>, <quic_sayalil@...cinc.com>
Subject: Re: [PATCH V4] mmc: sdhci-msm: Reset GCC_SDCC_BCR register for SDHC

Hi,

Thanks for the review.

Please find the inline comments.

Thanks,

Sajida

On 4/12/2022 4:30 PM, Philipp Zabel wrote:
> On Di, 2022-04-12 at 16:09 +0530, Shaik Sajida Bhanu wrote:
>> Reset GCC_SDCC_BCR register before every fresh initilazation. This will
>> reset whole SDHC-msm controller, clears the previous power control
>> states and avoids, software reset timeout issues as below.
>>
>> [ 5.458061][ T262] mmc1: Reset 0x1 never completed.
>> [ 5.462454][ T262] mmc1: sdhci: ============ SDHCI REGISTER DUMP ===========
>> [ 5.469065][ T262] mmc1: sdhci: Sys addr: 0x00000000 | Version: 0x00007202
>> [ 5.475688][ T262] mmc1: sdhci: Blk size: 0x00000000 | Blk cnt: 0x00000000
>> [ 5.482315][ T262] mmc1: sdhci: Argument: 0x00000000 | Trn mode: 0x00000000
>> [ 5.488927][ T262] mmc1: sdhci: Present: 0x01f800f0 | Host ctl: 0x00000000
>> [ 5.495539][ T262] mmc1: sdhci: Power: 0x00000000 | Blk gap: 0x00000000
>> [ 5.502162][ T262] mmc1: sdhci: Wake-up: 0x00000000 | Clock: 0x00000003
>> [ 5.508768][ T262] mmc1: sdhci: Timeout: 0x00000000 | Int stat: 0x00000000
>> [ 5.515381][ T262] mmc1: sdhci: Int enab: 0x00000000 | Sig enab: 0x00000000
>> [ 5.521996][ T262] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000
>> [ 5.528607][ T262] mmc1: sdhci: Caps: 0x362dc8b2 | Caps_1: 0x0000808f
>> [ 5.535227][ T262] mmc1: sdhci: Cmd: 0x00000000 | Max curr: 0x00000000
>> [ 5.541841][ T262] mmc1: sdhci: Resp[0]: 0x00000000 | Resp[1]: 0x00000000
>> [ 5.548454][ T262] mmc1: sdhci: Resp[2]: 0x00000000 | Resp[3]: 0x00000000
>> [ 5.555079][ T262] mmc1: sdhci: Host ctl2: 0x00000000
>> [ 5.559651][ T262] mmc1: sdhci_msm: ----------- VENDOR REGISTER DUMP-----------
>> [ 5.566621][ T262] mmc1: sdhci_msm: DLL sts: 0x00000000 | DLL cfg: 0x6000642c | DLL cfg2: 0x0020a000
>> [ 5.575465][ T262] mmc1: sdhci_msm: DLL cfg3: 0x00000000 | DLL usr ctl: 0x00010800 | DDR cfg: 0x80040873
>> [ 5.584658][ T262] mmc1: sdhci_msm: Vndr func: 0x00018a9c | Vndr func2 : 0xf88218a8 Vndr func3: 0x02626040
>>
>> Fixes: 0eb0d9f4de34 ("mmc: sdhci-msm: Initial support for Qualcomm chipsets")
>> Signed-off-by: Shaik Sajida Bhanu <quic_c_sbhanu@...cinc.com>
>> ---
>>   drivers/mmc/host/sdhci-msm.c | 38 ++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 38 insertions(+)
>>
>> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
>> index 50c71e0..0e5fb62 100644
>> --- a/drivers/mmc/host/sdhci-msm.c
>> +++ b/drivers/mmc/host/sdhci-msm.c
>> @@ -17,6 +17,7 @@
>>   #include <linux/regulator/consumer.h>
>>   #include <linux/interconnect.h>
>>   #include <linux/pinctrl/consumer.h>
>> +#include <linux/reset.h>
>>   
>>
>>
>>
>>   #include "sdhci-pltfm.h"
>>   #include "cqhci.h"
>> @@ -2482,6 +2483,39 @@ static inline void sdhci_msm_get_of_property(struct platform_device *pdev,
>>   	of_property_read_u32(node, "qcom,dll-config", &msm_host->dll_config);
>>   }
>>   
>>
>>
>>
>> +static int sdhci_msm_gcc_reset(struct device *dev, struct sdhci_host *host)
>> +{
>> +	struct reset_control *reset;
>> +	int ret = 0;
> No need to initialize ret.
>
>> +
>> +	reset = reset_control_get_optional_exclusive(dev, NULL);
>> +	if (IS_ERR(reset))
>> +		return dev_err_probe(dev, PTR_ERR(reset),
>> +				"unable to acquire core_reset\n");
>> +
>> +	if (!reset)
>> +		return ret;
Here we are returning ret directly if reset is NULL , so ret 
initialization is required.
>> +
>> +	ret = reset_control_assert(reset);
>> +	if (ret)
>> +		return dev_err_probe(dev, ret, "core_reset assert failed\n");
> Missing reset_control_put(reset) in the error path.
Sure will add
>
>> +
>> +	/*
>> +	 * The hardware requirement for delay between assert/deassert
>> +	 * is at least 3-4 sleep clock (32.7KHz) cycles, which comes to
>> +	 * ~125us (4/32768). To be on the safe side add 200us delay.
>> +	 */
>> +	usleep_range(200, 210);
>> +
>> +	ret = reset_control_deassert(reset);
>> +	if (ret)
>> +		return dev_err_probe(dev, ret, "core_reset deassert failed\n");
> Same as above. Maybe make both ret = dev_err_probe() and goto ...
In both cases error message is different so I think goto not good idea here.
>
>> +
>> +	usleep_range(200, 210);
> ... here.
>
>> +	reset_control_put(reset);
>> +
>> +	return ret;
>> +}
> regards
> Philipp