linux-kernel - Re: [PATCH v5 2/5] soc: qcom: llcc: Add regmap for Broadcast

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Date: Wed, 29 May 2024 10:09:56 -0700
From: Unnathi Chalicheemala <quic_uchalich@...cinc.com>
To: Bjorn Andersson <andersson@...nel.org>
CC: Konrad Dybcio <konrad.dybcio@...aro.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley
	<conor+dt@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kernel@...cinc.com>, Bjorn Andersson <quic_bjorande@...cinc.com>
Subject: Re: [PATCH v5 2/5] soc: qcom: llcc: Add regmap for Broadcast_AND
 region

On 5/26/2024 8:11 PM, Bjorn Andersson wrote:
> On Mon, May 20, 2024 at 02:00:14PM GMT, Unnathi Chalicheemala wrote:
>> Define new regmap structure for Broadcast_AND region and initialize
>> this regmap when HW block version is greater than 4.1, otherwise
>> initialize as a NULL pointer for backwards compatibility.
>>
>> Switch from broadcast_OR to broadcast_AND region (when defined in DT)
>> for checking status bit 1 as Broadcast_OR region checks only for bit 0.
>>
> 
> This is a good technical description of the change you're making. But
> it's been long enough since we discussed this that I've forgotten which
> problem it solves, and the commit message doesn't tell me.
> 
> Please add a paragraph on the top describing the actual problem this
> solves?
>
Yes understood, I'll append this to the commit message:

To support CSR programming, a broadcast interface is used to program all
channels in a single command. Until SM8450 there was only one broadcast
region (Broadcast_OR) used to broadcast write and check for status bit
0.
>From SM8450 onwards another broadcast region (Broadcast_AND) has been
added which checks for status bit 1. This hasn't been updated and
Broadcast_OR region was wrongly being used to check for status bit 1 all
along.

Thank you Bjorn.
> Regards,
> Bjorn
> 
>> Signed-off-by: Unnathi Chalicheemala <quic_uchalich@...cinc.com>
>> Reviewed-by: Bjorn Andersson <quic_bjorande@...cinc.com>
>> ---
>>  drivers/soc/qcom/llcc-qcom.c       | 16 +++++++++++++++-
>>  include/linux/soc/qcom/llcc-qcom.h |  4 +++-
>>  2 files changed, 18 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/soc/qcom/llcc-qcom.c b/drivers/soc/qcom/llcc-qcom.c
>> index cbef0dea1d5d..5eac6aa567e7 100644
>> --- a/drivers/soc/qcom/llcc-qcom.c
>> +++ b/drivers/soc/qcom/llcc-qcom.c
>> @@ -821,6 +821,7 @@ EXPORT_SYMBOL_GPL(llcc_slice_putd);
>>  static int llcc_update_act_ctrl(u32 sid,
>>  				u32 act_ctrl_reg_val, u32 status)
>>  {
>> +	struct regmap *regmap;
>>  	u32 act_ctrl_reg;
>>  	u32 act_clear_reg;
>>  	u32 status_reg;
>> @@ -849,7 +850,8 @@ static int llcc_update_act_ctrl(u32 sid,
>>  		return ret;
>>  
>>  	if (drv_data->version >= LLCC_VERSION_4_1_0_0) {
>> -		ret = regmap_read_poll_timeout(drv_data->bcast_regmap, status_reg,
>> +		regmap = drv_data->bcast_and_regmap ?: drv_data->bcast_regmap;
>> +		ret = regmap_read_poll_timeout(regmap, status_reg,
>>  				      slice_status, (slice_status & ACT_COMPLETE),
>>  				      0, LLCC_STATUS_READ_DELAY);
>>  		if (ret)
>> @@ -1284,6 +1286,18 @@ static int qcom_llcc_probe(struct platform_device *pdev)
>>  
>>  	drv_data->version = version;
>>  
>> +	/* Applicable only when drv_data->version >= 4.1 */
>> +	if (drv_data->version >= LLCC_VERSION_4_1_0_0) {
>> +		drv_data->bcast_and_regmap = qcom_llcc_init_mmio(pdev, i + 1, "llcc_broadcast_and_base");
>> +		if (IS_ERR(drv_data->bcast_and_regmap)) {
>> +			ret = PTR_ERR(drv_data->bcast_and_regmap);
>> +			if (ret == -EINVAL)
>> +				drv_data->bcast_and_regmap = NULL;
>> +			else
>> +				goto err;
>> +		}
>> +	}
>> +
>>  	llcc_cfg = cfg->sct_data;
>>  	sz = cfg->size;
>>  
>> diff --git a/include/linux/soc/qcom/llcc-qcom.h b/include/linux/soc/qcom/llcc-qcom.h
>> index 1a886666bbb6..9e9f528b1370 100644
>> --- a/include/linux/soc/qcom/llcc-qcom.h
>> +++ b/include/linux/soc/qcom/llcc-qcom.h
>> @@ -115,7 +115,8 @@ struct llcc_edac_reg_offset {
>>  /**
>>   * struct llcc_drv_data - Data associated with the llcc driver
>>   * @regmaps: regmaps associated with the llcc device
>> - * @bcast_regmap: regmap associated with llcc broadcast offset
>> + * @bcast_regmap: regmap associated with llcc broadcast OR offset
>> + * @bcast_and_regmap: regmap associated with llcc broadcast AND offset
>>   * @cfg: pointer to the data structure for slice configuration
>>   * @edac_reg_offset: Offset of the LLCC EDAC registers
>>   * @lock: mutex associated with each slice
>> @@ -129,6 +130,7 @@ struct llcc_edac_reg_offset {
>>  struct llcc_drv_data {
>>  	struct regmap **regmaps;
>>  	struct regmap *bcast_regmap;
>> +	struct regmap *bcast_and_regmap;
>>  	const struct llcc_slice_config *cfg;
>>  	const struct llcc_edac_reg_offset *edac_reg_offset;
>>  	struct mutex lock;
>> -- 
>> 2.34.1
>>