linux-kernel - Re: [PATCH V4 1/3] pci: Add PCIe driver for Samsung Exynos

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Date:	Thu, 20 Jun 2013 16:56:29 +0530
From:	Pratyush Anand <pratyush.anand@...com>
To:	Jingoo Han <jg1.han@...sung.com>, 'Arnd Bergmann' <arnd@...db.de>,
	Mohit KUMAR <Mohit.KUMAR@...com>
Cc:	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Bjorn Helgaas' <bhelgaas@...gle.com>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	'Grant Likely' <grant.likely@...retlab.ca>,
	'Andrew Murray' <andrew.murray@....com>,
	'Thomas Petazzoni' <thomas.petazzoni@...e-electrons.com>,
	'Thierry Reding' <thierry.reding@...onic-design.de>,
	'Jason Gunthorpe' <jgunthorpe@...idianresearch.com>,
	'Surendranath Gurivireddy Balla' <suren.reddy@...sung.com>,
	'Siva Reddy Kallam' <siva.kallam@...sung.com>,
	'Thomas Abraham' <thomas.abraham@...aro.org>
Subject: Re: [PATCH V4 1/3] pci: Add PCIe driver for Samsung Exynos

Hi,

On 6/20/2013 4:28 PM, Jingoo Han wrote:
> On Thursday, June 20, 2013 6:59 PM, Pratyush Anand wrote:
>> On 6/13/2013 7:48 PM, Arnd Bergmann wrote:
>>> On Thursday 13 June 2013 22:18:50 Jingoo Han wrote:
>>>>> On Wednesday, June 12, 2013 8:23 PM, Arnd Bergmann wrote:
>>>>>>> On Wednesday 12 June 2013 19:19:05 Jingoo Han wrote:
>>>>>>>>> +
>>>>>>>>> +/* synopsis specific PCIE configuration registers*/
>>>>>>>>> +#define PCIE_PORT_LINK_CONTROL		0x710
>>>>>>>>> +#define PORT_LINK_MODE_MASK		(0x3f << 16)
>>>>>>>>> +#define PORT_LINK_MODE_4_LANES		(0x7 << 16)
>>>>>>>
>>>>>>> Do you mean this is a "Synopsys" designware part? In that case it
>>>>>>> should really not be called "exynos-pcie" but "designware-pcie"
>>>>>>> and you should make sure that the driver makes no assumptions about
>>>>>>> the platform. A lot of other platforms also use designware
>>>>>>> parts and should be able to reuse this driver.
>>>>>
>>>>> Sorry, I don't think so.
>>>>> Only core block is a "Synopsys" designware part IP block,
>>>>> other parts are Exynos-specific.
>>>>> So, it is hard to share with other PCIe IPs using synopsis core.
>>> Just call it synopsys anyway and put a comment in to explain this.
>>> That should be enough for the next person with a synopsys PCI core
>>> to reuse your code and split out the exynos specific parts into a
>>> separate file.
>>>
>>
>> I agree to Arnd that this patch should be split. I had worked in past
>> with SPEAr PCIe which also had designware PCIe IP. I see some code which
>> will fit both in SPEAr as well as in exynos. Unfortunately, I was not
>> able to get SPEAr driver pushed to mainline, as I moved to some other
>> project and got heavily occupied.
>
> Oh, I see.
>
> How about this?
> At the next PATCH v7, I will change the file name from 'pci-exynos.c'
> to 'pci-designware.c', as Arnd mentioned.
>
> Then, when Spear or other platform using designware is submitted,
> this 'pci-designware.c' will be split to two separate files such as
> 'pci-designware.c' and 'pci-exynos.c'.
>

For me it's OK. Let it go to mainline as Arnd mentioned.
Please keep Mohit in mail chain, who might have some bandwidth to 
further add and follow up for SPEAr on top of your patches.

Regards
Pratyush

>
> Best regards,
> Jingoo Han
>
>>
>> Last patch is here:
>>
>> https://patchwork.kernel.org/patch/1661441/
>>
>> Infact, these functions should be common to all arm platforms.
>>
>> sys_to_pcie
>> cfg_read
>> cfg_write
>>
>> Following functions should be common to all designware based driver (at
>> least they are same in SPEAr)
>>
>> exynos_pcie_prog_viewport_cfg0
>> exynos_pcie_prog_viewport_cfg1
>> exynos_pcie_rd_other_conf
>> exynos_pcie_wr_other_conf
>> exynos_pcie_setup
>> exynos_pcie_valid_config
>> exynos_pcie_rd_conf
>> exynos_pcie_wd_conf
>> exynos_pcie_scan_bus
>> exynos_pcie_map_irq
>> add_pcie_port (after a bit of generalization)
>> exynos_pcie_probe
>> exynos_pcie_remove
>>
>>
>>
>> Following should be specific to exynos:
>>
>> exynos_pcie_rd_own_conf
>> exynos_pcie_wr_own_conf
>> exynos_pcie_link_up
>> exynos_pcie_setup_rc
>> exynos_pcie_assert_core_reset
>> exynos_pcie_deassert_core_reset
>> exynos_pcie_assert_phy_reset
>> exynos_pcie_deassert_phy_reset
>> exynos_pcie_init_phy
>> exynos_pcie_assert_reset
>> exynos_pcie_establish_link
>> exynos_pcie_host_init
>>
>>
>>
>> struct pcie_port_info and struct pcie_port can also be standardized.
>>
>> Regards
>> Pratyush
>
> .
>


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