Date:	Wed, 3 Feb 2016 15:01:34 +0000
From:	Joao Pinto <Joao.Pinto@...opsys.com>
To:	Arnd Bergmann <arnd@...db.de>, Joao Pinto <Joao.Pinto@...opsys.com>
CC:	<santosh.sy@...sung.com>, <h.vinayak@...sung.com>,
	<julian.calaby@...il.com>, <akinobu.mita@...il.com>,
	<hch@...radead.org>, <gbroner@...eaurora.org>,
	<subhashj@...eaurora.org>, <CARLOS.PALMINHA@...opsys.com>,
	<ijc+devicetree@...lion.org.uk>, <linux-kernel@...r.kernel.org>,
	<linux-scsi@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH 3/3] add support for DWC UFS Host Controller


Hi Arnd,

On 2/3/2016 12:54 PM, Arnd Bergmann wrote:
> On Wednesday 03 February 2016 11:28:26 Joao Pinto wrote:
>>
>> Signed-off-by: Joao Pinto <jpinto@...opsys.com>
> 
> This needs a changelog comment, like every patch.
> 
>> @@ -0,0 +1,16 @@
>> +* Universal Flash Storage (UFS) DesignWare Host Controller
>> +
>> +DWC_UFSHC nodes are defined to describe on-chip UFS host controllers.
>> +Each UFS controller instance should have its own node.
>> +
>> +Required properties:
>> +- compatible        : compatible list, contains "snps,ufshcd"
> 
> Are there multiple versions of this controller? Usually for designware
> parts the version is known, so we should document which versions exist

This controller recent releases was 2.0, but we released last year 1.1. The
driver works with both. The driver must work with all DWC UFS versions.

> 
>> +
>> +config SCSI_UFS_DWC_HOOKS
>> +	bool "DesignWare hooks to UFS controller"
>> +	depends on SCSI_UFSHCD
>> +	---help---
>> +	  This selects the DesignWare hooks for the UFS host controller.
>> +
>> +	  Select this if you have a DesignWare UFS controller.
>> +	  If unsure, say N.
> 
> This could be a silent symbol that gets selected by SCSI_UFS_DWC_PLAT

We could do that, but imagine that we select SCSI_UFS_QCOM, then the synopsys
hooks would be selected also which in my opinion is not very accurate.
In my opinion we should have a selectable DWC_HOOKS.

> 
>> +config SCSI_UFS_DWC_MPHY_TC
>> +	bool "Support for the Synopsys MPHY Test Chip"
>> +	depends on SCSI_UFS_DWC_HOOKS && (SCSI_UFSHCD_PCI || SCSI_UFS_DWC_PLAT)
>> +	---help---
>> +	  This selects the support for the Synopsys MPHY Test Chip.
>> +
>> +	  Select this if you have a Synopsys MPHY Test Chip.
>> +	  If unsure, say N.
>> +
>> +config SCSI_UFS_DWC_20BIT_RMMI
>> +	bool "20-bit RMMI MPHY"
>> +	depends on SCSI_UFS_DWC_MPHY_TC
>> +	---help---
>> +	  This specifies that the Synopsys MPHY supports 40-bit RMMI operations.
>> +
>> +	  Select this if you are using a 40-bit RMMI Synopsys MPHY.
>> +	  If unsure, say N.
>> +
>> +config SCSI_UFS_DWC_40BIT_RMMI
>> +	bool "40-bit RMMI MPHY"
>> +	depends on SCSI_UFS_DWC_MPHY_TC
>> +	---help---
>> +	  This specifies that the Synopsys MPHY supports 40-bit RMMI operations.
>> +
>> +	  Select this if you are using a 40-bit RMMI Synopsys MPHY.
>> +	  If unsure, say N.
> 
> Move the PHY config options to drivers/phy/ along with the respective
> drivers, the device using the PHY should not need to be aware which
> one is being used.

This MPHY config is just to enable parts of the host config which consists of
specific unipro commands and nothing else. The unipro command execution uses
functions that are in the ufshcd.c. But if everyone agree we can do as you suggest.

> 
>> +/**
>> + * ufshcd_dwc_setup_mphy()
>> + * This function configures Local (host) Synopsys MPHY specific attributes
>> + *
>> + * @hba: Pointer to drivers structure
>> + *
>> + * Returns 0 on success non-zero value on failure
>> + */
>> +int ufshcd_dwc_setup_mphy(struct ufs_hba *hba)
>> +{
>> +	int ret = 0;
>> +
>> +#ifdef CONFIG_SCSI_UFS_DWC_40BIT_RMMI
>> +	dev_info(hba->dev, "Configuring MPHY 40-bit RMMI");
>> +	ret = ufshcd_dwc_setup_40bit_rmmi(hba);
>> +	if (ret) {
>> +		dev_err(hba->dev, "40-bit RMMI configuration failed");
>> +		goto out;
>> +	}
>> +#else
>> +#ifdef CONFIG_SCSI_UFS_DWC_20BIT_RMMI
>> +	dev_info(hba->dev, "Configuring MPHY 20-bit RMMI");
>> +	ret = ufshcd_dwc_setup_20bit_rmmi(hba);
>> +	if (ret) {
>> +		dev_err(hba->dev, "20-bit RMMI configuration failed");
>> +		goto out;
>> +	}
>> +#endif
>> +#endif
>> +	/* To write Shadow register bank to effective configuration block */
>> +	ret = ufshcd_dme_set(hba, UIC_ARG_MIB(VS_MPHYCFGUPDT), 0x01);
>> +	if (ret)
>> +		goto out;
>> +
>> +	/* To configure Debug OMC */
>> +	ret = ufshcd_dme_set(hba, UIC_ARG_MIB(VS_DEBUGOMC), 0x01);
>> +
>> +out:
>> +	return ret;
>> +}
> 
> Try to use the generic PHY abstraction here and remove all the #ifdef etc.

Could you please point an example for me to check?

> 
>> diff --git a/drivers/scsi/ufs/ufshcd-pci.c b/drivers/scsi/ufs/ufshcd-pci.c
>> index d15eaa4..66518a1 100644
>> --- a/drivers/scsi/ufs/ufshcd-pci.c
>> +++ b/drivers/scsi/ufs/ufshcd-pci.c
>> @@ -34,6 +34,9 @@
>>   */
>>  
>>  #include "ufshcd.h"
>> +#ifdef CONFIG_SCSI_UFS_DWC_HOOKS
>> +#include "ufshcd-dwc.h"
>> +#endif
>>  #include <linux/pci.h>
>>  #include <linux/pm_runtime.h>
>>  
>> @@ -83,6 +86,16 @@ static int ufshcd_pci_runtime_idle(struct device *dev)
>>  #define ufshcd_pci_runtime_idle	NULL
>>  #endif /* CONFIG_PM */
>>  
>> +#ifdef CONFIG_SCSI_UFS_DWC_HOOKS
>> +/**
>> + * struct ufs_hba_dwc_vops - UFS DWC specific variant operations
>> + */
>> +static struct ufs_hba_variant_ops ufs_dwc_pci_hba_vops = {
>> +	.name                   = "dwc-pci",
>> +	.custom_probe_hba	= ufshcd_dwc_configuration,
>> +};
>> +#endif
>> +
>>  /**
>>   * ufshcd_pci_shutdown - main function to put the controller in reset state
>>   * @pdev: pointer to PCI device handle
>> @@ -144,6 +157,9 @@ ufshcd_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>>  
>>  	INIT_LIST_HEAD(&hba->clk_list_head);
>>  
>> +#ifdef CONFIG_SCSI_UFS_DWC_HOOKS
>> +	hba->vops = &ufs_dwc_pci_hba_vops;
>> +#endif
>>  	err = ufshcd_init(hba, mmio_base, pdev->irq);
>>  	if (err) {
>>  		dev_err(&pdev->dev, "Initialization failed\n");
>> @@ -167,6 +183,10 @@ static const struct dev_pm_ops ufshcd_pci_pm_ops = {
>>  
>>  static const struct pci_device_id ufshcd_pci_tbl[] = {
>>  	{ PCI_VENDOR_ID_SAMSUNG, 0xC00C, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
>> +#ifdef CONFIG_SCSI_UFS_DWC_HOOKS
>> +	{ PCI_VENDOR_ID_SYNOPSYS, 0xB101, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
>> +	{ PCI_VENDOR_ID_SYNOPSYS, 0xB102, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
>> +#endif
>>  	{ }	/* terminate list */
>>  };
> 
> I think you're better off with a separate PCI driver for this. Remove
> all the #ifdef mess here, put whatever is dwc specific into a new file,
> and perhaps move the common parts into a shared file that can be used
> by both the samsung and designware drivers.

I have a branch with that approach, but honestly it would be a big change in the
UFS arch for the pci and I decided to make it simple. I sent that suggestion for
the scsi mailing list and the comments showed me that. Does anyone have anything
against putting ufshcd-pci.c as a pci common code and then have a ufs-dwc-pci.c
and a ufs-samsung-pci.c that uses that common code?

> 
> 	Arnd
> 

Thanks,
Joao

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