linux-kernel - Re: [PATCH v11 4/6] PCI: hisi: Add PCIe host support for HiSilicon SoC Hip05

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Date:	Mon, 26 Oct 2015 16:24:34 +0800
From:	Zhou Wang <wangzhou1@...ilicon.com>
To:	Bjorn Helgaas <helgaas@...nel.org>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>, <jingoohan1@...il.com>,
	<pratyush.anand@...il.com>, Arnd Bergmann <arnd@...db.de>,
	<linux@....linux.org.uk>, <thomas.petazzoni@...e-electrons.com>,
	<gabriele.paoloni@...wei.com>, <lorenzo.pieralisi@....com>,
	<james.morse@....com>, <Liviu.Dudau@....com>,
	<jason@...edaemon.net>, <robh@...nel.org>,
	<gabriel.fernandez@...aro.org>, <Minghuan.Lian@...escale.com>,
	<linux-pci@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<zhangjukuo@...wei.com>, <qiuzhenfa@...ilicon.com>,
	<liudongdong3@...wei.com>, <qiujiang@...wei.com>,
	<xuwei5@...ilicon.com>, <liguozhu@...ilicon.com>
Subject: Re: [PATCH v11 4/6] PCI: hisi: Add PCIe host support for HiSilicon
 SoC Hip05

On 2015/10/23 2:46, Bjorn Helgaas wrote:
> Hi Zhou,
> 
> This looks pretty good to me; just a mask question and add a printk.
> 
> On Fri, Oct 16, 2015 at 06:23:39PM +0800, Zhou Wang wrote:
>> This patch adds PCIe host support for HiSilicon SoC Hip05.
>> ...
> 
>> +#define PCIE_SUBCTRL_SYS_STATE4_REG                     0x6818
>> +#define PCIE_LTSSM_LINKUP_STATE                         0x11
>> +#define PCIE_LTSSM_STATE_MASK                           0x3F
> 
> Fabio unified some of this; see
>   https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/commit/?h=pci/host-designware&id=4788fe6ebf4594c9a95b620cbff05147c8504823
>   https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/commit/?h=pci/host-designware&id=b09464f77dd252a782da1f4e9925c1dbce4540ac
> 
> So the question is, why do you use a 6-bit (0x3f) LTSSM_STATE_MASK?
> We think we can use a 5-bit mask (0x1f) for all the other
> DesignWare-based systems.

Hi Bjorn,

LTSSM_STATE_MASK indicates the status of LTSSM, it should be 6-bit
in Hip05 PCIe host. I checked Designware hardware manual, its
LTSSM current state is 6-bit too(smlh_ltssm_state).

> 
>> +/* Hip05 PCIe host only supports 32-bit config access */
> 
> Thanks for the comment asserting that Hip05 only supports 32-bit
> config access.  I assume you confirmed that with the hardware
> designers.  As far as I can tell, this *is* a hardware defect, and at
> the minimum, I want a printk at driver probe-time so a dmesg log will
> have a clue that read/modify/write on config space might do the wrong
> thing.
>

Yes, I had checked this with hardware guys. Will add a print during probe-time.

Many thanks,
Zhou

>> +static int hisi_pcie_cfg_read(struct pcie_port *pp, int where, int size,
>> +			      u32 *val)
>> ...
> 
> Bjorn
> 
> .
> 


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