linux-kernel - Re: [PATCH v2 1/1] mmc: sdhci-of-dwcmshc: add callback functions for dwcmshc

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Date: Thu, 9 May 2024 10:17:50 +0800
From: Chen Wang <unicorn_wang@...look.com>
To: Adrian Hunter <adrian.hunter@...el.com>, Chen Wang <unicornxw@...il.com>,
 ulf.hansson@...aro.org, linux-mmc@...r.kernel.org,
 linux-kernel@...r.kernel.org, jszhang@...nel.org, dfustini@...libre.com,
 yifeng.zhao@...k-chips.com, shawn.lin@...k-chips.com, chao.wei@...hgo.com,
 haijiao.liu@...hgo.com, xiaoguang.xing@...hgo.com, tingzhu.wang@...hgo.com,
 guoren@...nel.org, inochiama@...look.com, unicorn_wang@...look.com
Subject: Re: [PATCH v2 1/1] mmc: sdhci-of-dwcmshc: add callback functions for
 dwcmshc_priv


On 2024/4/29 15:08, Adrian Hunter wrote:
> On 28/04/24 05:32, Chen Wang wrote:
>> From: Chen Wang <unicorn_wang@...look.com>
>>
>> The current framework is not easily extended to support new SOCs.
>> For example, in the current code we see that the SOC-level
>> structure `rk35xx_priv` and related logic are distributed in
>> functions such as dwcmshc_probe/dwcmshc_remove/dwcmshc_suspend/......,
>> which is inappropriate.
>>
>> The solution is to abstract some possible common operations of soc
>> into virtual members of `dwcmshc_priv`. Each soc implements its own
>> corresponding callback function and registers it in init function.
>> dwcmshc framework is responsible for calling these callback functions
>> in those dwcmshc_xxx functions.
>>
>> Signed-off-by: Chen Wang <unicorn_wang@...look.com>
>> ---
>>   drivers/mmc/host/sdhci-of-dwcmshc.c | 152 +++++++++++++++++-----------
>>   1 file changed, 91 insertions(+), 61 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
>> index 39edf04fedcf..525f954bcb65 100644
>> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
>> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
>> @@ -214,6 +214,10 @@ struct dwcmshc_priv {
>>   	void *priv; /* pointer to SoC private stuff */
>>   	u16 delay_line;
>>   	u16 flags;
>> +
>> +	void (*soc_postinit)(struct sdhci_host *host, struct dwcmshc_priv *dwc_priv);
>> +	int (*soc_clks_enable)(struct dwcmshc_priv *dwc_priv);
>> +	void (*soc_clks_disable)(struct dwcmshc_priv *dwc_priv);
> Normally the ops would be part of platform data.  For example,
> sdhci-of-arasan.c has:
>
> 	struct sdhci_arasan_of_data {
> 		const struct sdhci_arasan_soc_ctl_map *soc_ctl_map;
> 		const struct sdhci_pltfm_data *pdata;
> 		const struct sdhci_arasan_clk_ops *clk_ops;
> 	};
>
> And then:
>
> 	static struct sdhci_arasan_of_data sdhci_arasan_rk3399_data = {
> 		.soc_ctl_map = &rk3399_soc_ctl_map,
> 		.pdata = &sdhci_arasan_cqe_pdata,
> 		.clk_ops = &arasan_clk_ops,
> 	};
> 	etc
>
> 	static const struct of_device_id sdhci_arasan_of_match[] = {
> 		/* SoC-specific compatible strings w/ soc_ctl_map */
> 		{
> 			.compatible = "rockchip,rk3399-sdhci-5.1",
> 			.data = &sdhci_arasan_rk3399_data,
> 		},
> 		etc
>
> So, say:
>
> struct dwcmshc_pltfm_data {
> 	const struct sdhci_pltfm_data *pltfm_data;
> 	void (*postinit)(struct sdhci_host *host, struct dwcmshc_priv *dwc_priv);
> 	int  (*clks_enable)(struct dwcmshc_priv *dwc_priv);
> 	void (*clks_disable)(struct dwcmshc_priv *dwc_priv);
> }
>
> Or if the ops are mostly the same, it might be more convenient to
> have them in their own structure:
>
> struct dwcmshc_pltfm_data {
> 	const struct sdhci_pltfm_data *pltfm_data;
> 	const struct dwcmshc_ops *ops;
> }

hi, Adrian,

I thought about it for a while, and I would like to continue discussing 
this issue as follows.

I feel like it would be simpler to put it at the dwcmshc_priv level 
based on the ops involved in the code so far. Judging from the SOCs 
currently supported by dwcmshc, the ops I abstracted only operate data 
below the dwcmshc_priv level, and these ops are not used by most SOCs.
- postinit: only required by rk35xx
- init: involves rk35xx and th1520, and the new soc(sg2042) I want to add.
- clks_enable/clks_disable: only rk35xx and the sg2042 I want to add

In particular, for dwcmshc_suspend/dwcmshc_resume, we have already 
obtained dwcmshc_priv. If ops is to be placed at the platformdata level, 
we have to use device_get_match_data to obtain data again, which feels a 
bit unnecessary.

What do you think?

Thanks,

Chen

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