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

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Message-id: <00d701ce6da5$10216ae0$306440a0$@samsung.com>
Date:	Thu, 20 Jun 2013 19:58:14 +0900
From:	Jingoo Han <jg1.han@...sung.com>
To:	'Pratyush Anand' <pratyush.anand@...com>,
	'Arnd Bergmann' <arnd@...db.de>
Cc:	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Bjorn Helgaas' <bhelgaas@...gle.com>,
	linux-samsung-soc@...r.kernel.org, linux-pci@...r.kernel.org,
	devicetree-discuss@...ts.ozlabs.org,
	linux-arm-kernel@...ts.infradead.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>,
	'Mohit KUMAR' <Mohit.KUMAR@...com>,
	Jingoo Han <jg1.han@...sung.com>
Subject: Re: [PATCH V4 1/3] pci: Add PCIe driver for Samsung Exynos

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'.


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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