From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Date: Thu, 06 Apr 2017 18:24:01 +0900 Subject: [U-Boot] [PATCH v1] mmc: sdhci: SDHCI controllers also need power In-Reply-To: References: <20170315182521.4359-1-andriy.shevchenko@linux.intel.com> <1490014266.19767.101.camel@linux.intel.com> <1491052273.708.95.camel@linux.intel.com> Message-ID: <1354bacc-4ad5-91c4-c3d1-0b28cdf09617@samsung.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 04/06/2017 05:51 PM, Andy Shevchenko wrote: > On Thu, Apr 6, 2017 at 6:44 AM, Simon Glass wrote: >> On 1 April 2017 at 07:11, Andy Shevchenko >> wrote: >>> On Fri, 2017-03-31 at 22:24 -0600, Simon Glass wrote: >>>> On 20 March 2017 at 06:51, Andy Shevchenko >>>> wrote: >>>>> On Sun, 2017-03-19 at 20:30 -0600, Simon Glass wrote: >>>>>> On 15 March 2017 at 12:25, Andy Shevchenko >>>>>> wrote: > >>>>>>> + board_mmc_power_init(); > >>>>>> You should be using driver model for this (CONFIG_DM_MMC*). >>>>> >>>>> I didn't get this part. It's used by the driver (tangier_sdhci) as >>>>> far >>>>> as I understand. > >>> Oh, we are talking about host controller's power management which is >>> done using PMU (power management unit) inside SoC. It's *not* a power >>> regulator. >>> >>> Above is clearly about card power management, which we also have (in >>> case of Wi-Fi), but it's not applicable for eMMC soldered on the module. >> >> Still if the eMMC is soldered on, it needs power, right? What is the >> distinction? > > It's irrelevant to this patch and discussion. > >> In any case we cannot call board code from the driver with DM - it's >> just not how things work. So can you init it in your board_init() code >> perhaps, if you can't use a power driver? > > I didn't get this either. > > It means that PMU driver should *not* go with DM model then or what? > >>>>>> or do this in >>>>>> the board code. >>>>> >>>>> How? It's already board code that powers on the controller. If you >>>>> look >>>>> at mmc_init() it does this. SDHCI on the other hand doesn't which is >>>>> for >>>>> my opinion is a bug. Otherwise why is the difference between >>>>> initialization sequence of MMC and SHDCI controllers? >>>> >>>> There should not really be a different I think, except that with >>>> driver model we want to use drivers for power rather than hard-coding >>>> things in custom code. >>> >>> I totally agree with this, though since we have no clear PCI >>> implementation on that board (*) we can't have good described PCI power >>> management for it. >>> >>> (*) It's called "fake PCI" meaning it mimics PCI programming interface >>> while being not 100% compatible with PCI specification on hardware and >>> firmware levels. >>> >>> So, for now I have been seeing no alternatives than my initial approach, >>> though I'm all ears for better solution. >> > >> Well you can create a regulator driver which has a single regulator to >> handle whatever needs doing to enable MMC power. > > No. It looks like you are mixing two power controls: card itself and > host controller. They are using quite different mechanisms to be > powered on. > We are talking here about *host* controller power flow. > > And still there is no clarification why MMC flow calls board code and > on the other hand you made an objectiion to do the same for SDHCI. > > I still do not see better solution as mine initial one, otherwise > above question should be clarified first. how about mmc_power_init() is called in mmc_probe()? >