From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH 2/3] mmc: dw_mmc: add dw_mmc-k3 for k3 platform Date: Mon, 30 Dec 2013 08:55:14 +0900 Message-ID: <52C0B662.4070608@samsung.com> References: <1388241295-20051-1-git-send-email-zhangfei.gao@linaro.org> <1388241295-20051-3-git-send-email-zhangfei.gao@linaro.org> <201312292205.02135.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <201312292205.02135.arnd@arndb.de> Sender: linux-mmc-owner@vger.kernel.org To: Arnd Bergmann , Zhangfei Gao Cc: Chris Ball , Mike Turquette , Rob Herring , Seungwon Jeon , Kumar Gala , Haojian Zhuang , linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, patches@linaro.org, devicetree@vger.kernel.org, Zhigang Wang , cpgs@samsung.com List-Id: devicetree@vger.kernel.org On 12/30/2013 06:05 AM, Arnd Bergmann wrote: > On Saturday 28 December 2013, Zhangfei Gao wrote: >> Add dw_mmc-k3.c for k3v2, support sd/emmc >> >> Signed-off-by: Zhangfei Gao >> Signed-off-by: Zhigang Wang >> --- >> .../devicetree/bindings/mmc/k3-dw-mshc.txt | 60 ++++++++++ >> drivers/mmc/host/Kconfig | 10 ++ >> drivers/mmc/host/Makefile | 1 + >> drivers/mmc/host/dw_mmc-k3.c | 126 ++++++++++++++++++++ >> 4 files changed, 197 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt >> create mode 100644 drivers/mmc/host/dw_mmc-k3.c >> >> diff --git a/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt >> new file mode 100644 >> index 000000000000..d7e2d7f159bb >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt >> @@ -0,0 +1,60 @@ >> +* Hisilicon specific extensions to the Synopsys Designware Mobile >> + Storage Host Controller >> + >> +Read synopsys-dw-mshc.txt for more details >> + >> +The Synopsys designware mobile storage host controller is used to interface >> +a SoC with storage medium such as eMMC or SD/MMC cards. This file documents >> +differences between the core Synopsys dw mshc controller properties described >> +by synopsys-dw-mshc.txt and the properties used by the Hisilicon specific >> +extensions to the Synopsys Designware Mobile Storage Host Controller. >> + >> +Required Properties: >> + >> +* compatible: should be one of the following. >> + - "hisilicon,hi4511-dw-mshc": for controllers with hi4511 specific extentions. > > I wonder if this is actually a different variant of the mshc hardware, or just > wired up in a different way. Do you know details? > > Since the only difference in the binding is the presence of the "clock-freq-table" > property, we could also make this property generic for the mshc driver and use > it if present but fall back to the normal behavior when it is absent. > >> +* clock-freq-table: should be the frequency (in Hz) array of the ciu clock >> + in each supported mode. >> + 0. CIU clock rate in Hz for DS mode >> + 1. CIU clock rate in Hz for MMC HS mode >> + 2. CIU clock rate in Hz for SD HS mode >> + 3. CIU clock rate in Hz for SDR12 mode >> + 4. CIU clock rate in Hz for SDR25 mode >> + 5. CIU clock rate in Hz for SDR50 mode >> + 6. CIU clock rate in Hz for SDR104 mode >> + 7. CIU clock rate in Hz for DDR50 mode >> + 8. CIU clock rate in Hz for HS200 mode > > This looks god now. > >> +static void dw_mci_k3_set_ios(struct dw_mci *host, struct mmc_ios *ios) >> +{ >> + struct dw_mci_k3_priv_data *priv = host->priv; >> + u32 rate = priv->clk_table[ios->timing]; >> + int ret; > > I think this should have some range checking to see if the mode that is > being set had a clock frequency set in the DT. > >> + >> + ret = clk_set_rate(host->ciu_clk, rate); >> + if (ret) >> + dev_warn(host->dev, "failed to set clock rate %uHz\n", rate); >> + >> + host->bus_hz = clk_get_rate(host->ciu_clk); >> +} > > Why do you call clk_get_rate() here, shouldn't it always be the same > rate that you have just set? > >> +static int dw_mci_k3_parse_dt(struct dw_mci *host) >> +{ >> + struct dw_mci_k3_priv_data *priv; >> + struct device_node *node = host->dev->of_node; >> + struct property *prop; >> + const __be32 *cur; >> + u32 val, num = 0; >> + >> + priv = devm_kzalloc(host->dev, sizeof(*priv), GFP_KERNEL); >> + if (!priv) { >> + dev_err(host->dev, "mem alloc failed for private data\n"); >> + return -ENOMEM; >> + } >> + host->priv = priv; >> + >> + of_property_for_each_u32(node, "clock-freq-table", prop, cur, val) { >> + if (num >= MAX_NUMS) >> + break; >> + priv->clk_table[num++] = val; >> + } >> + return 0; >> +} > > If we make this property part of the generic binding, this function could > also get moved to the main dw_mci driver. > >> +static int dw_mci_k3_suspend(struct device *dev) >> +{ >> + struct dw_mci *host = dev_get_drvdata(dev); >> + int ret = 0; >> + >> + ret = dw_mci_suspend(host); > > You should never initialize local variables when they are set later in the > function (the ret = 0 part above). For more complex functions, this prevents > gcc from warning you about accidentally uninitialized uses. > >> + if (!ret) >> + clk_disable_unprepare(host->ciu_clk); >> + >> + return ret; >> +} > > The suspend/resume code also looks very generic. Can't we make these the > default for dw-mci? If you do both, you won't even need a k3 specific driver. > I think in general we should try hard to add code like this to the common > driver when there is a chance that it can be shared with other platforms. Dw-mmc has the LOW_POWER mode feature at CLKENA register, this feature is running like clock-gating. So i have known it didn't control clock enable/disable in dw-mmc.c. Best Regards, Jaehoon Chung > > Arnd > From mboxrd@z Thu Jan 1 00:00:00 1970 From: jh80.chung@samsung.com (Jaehoon Chung) Date: Mon, 30 Dec 2013 08:55:14 +0900 Subject: [PATCH 2/3] mmc: dw_mmc: add dw_mmc-k3 for k3 platform In-Reply-To: <201312292205.02135.arnd@arndb.de> References: <1388241295-20051-1-git-send-email-zhangfei.gao@linaro.org> <1388241295-20051-3-git-send-email-zhangfei.gao@linaro.org> <201312292205.02135.arnd@arndb.de> Message-ID: <52C0B662.4070608@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/30/2013 06:05 AM, Arnd Bergmann wrote: > On Saturday 28 December 2013, Zhangfei Gao wrote: >> Add dw_mmc-k3.c for k3v2, support sd/emmc >> >> Signed-off-by: Zhangfei Gao >> Signed-off-by: Zhigang Wang >> --- >> .../devicetree/bindings/mmc/k3-dw-mshc.txt | 60 ++++++++++ >> drivers/mmc/host/Kconfig | 10 ++ >> drivers/mmc/host/Makefile | 1 + >> drivers/mmc/host/dw_mmc-k3.c | 126 ++++++++++++++++++++ >> 4 files changed, 197 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt >> create mode 100644 drivers/mmc/host/dw_mmc-k3.c >> >> diff --git a/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt >> new file mode 100644 >> index 000000000000..d7e2d7f159bb >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt >> @@ -0,0 +1,60 @@ >> +* Hisilicon specific extensions to the Synopsys Designware Mobile >> + Storage Host Controller >> + >> +Read synopsys-dw-mshc.txt for more details >> + >> +The Synopsys designware mobile storage host controller is used to interface >> +a SoC with storage medium such as eMMC or SD/MMC cards. This file documents >> +differences between the core Synopsys dw mshc controller properties described >> +by synopsys-dw-mshc.txt and the properties used by the Hisilicon specific >> +extensions to the Synopsys Designware Mobile Storage Host Controller. >> + >> +Required Properties: >> + >> +* compatible: should be one of the following. >> + - "hisilicon,hi4511-dw-mshc": for controllers with hi4511 specific extentions. > > I wonder if this is actually a different variant of the mshc hardware, or just > wired up in a different way. Do you know details? > > Since the only difference in the binding is the presence of the "clock-freq-table" > property, we could also make this property generic for the mshc driver and use > it if present but fall back to the normal behavior when it is absent. > >> +* clock-freq-table: should be the frequency (in Hz) array of the ciu clock >> + in each supported mode. >> + 0. CIU clock rate in Hz for DS mode >> + 1. CIU clock rate in Hz for MMC HS mode >> + 2. CIU clock rate in Hz for SD HS mode >> + 3. CIU clock rate in Hz for SDR12 mode >> + 4. CIU clock rate in Hz for SDR25 mode >> + 5. CIU clock rate in Hz for SDR50 mode >> + 6. CIU clock rate in Hz for SDR104 mode >> + 7. CIU clock rate in Hz for DDR50 mode >> + 8. CIU clock rate in Hz for HS200 mode > > This looks god now. > >> +static void dw_mci_k3_set_ios(struct dw_mci *host, struct mmc_ios *ios) >> +{ >> + struct dw_mci_k3_priv_data *priv = host->priv; >> + u32 rate = priv->clk_table[ios->timing]; >> + int ret; > > I think this should have some range checking to see if the mode that is > being set had a clock frequency set in the DT. > >> + >> + ret = clk_set_rate(host->ciu_clk, rate); >> + if (ret) >> + dev_warn(host->dev, "failed to set clock rate %uHz\n", rate); >> + >> + host->bus_hz = clk_get_rate(host->ciu_clk); >> +} > > Why do you call clk_get_rate() here, shouldn't it always be the same > rate that you have just set? > >> +static int dw_mci_k3_parse_dt(struct dw_mci *host) >> +{ >> + struct dw_mci_k3_priv_data *priv; >> + struct device_node *node = host->dev->of_node; >> + struct property *prop; >> + const __be32 *cur; >> + u32 val, num = 0; >> + >> + priv = devm_kzalloc(host->dev, sizeof(*priv), GFP_KERNEL); >> + if (!priv) { >> + dev_err(host->dev, "mem alloc failed for private data\n"); >> + return -ENOMEM; >> + } >> + host->priv = priv; >> + >> + of_property_for_each_u32(node, "clock-freq-table", prop, cur, val) { >> + if (num >= MAX_NUMS) >> + break; >> + priv->clk_table[num++] = val; >> + } >> + return 0; >> +} > > If we make this property part of the generic binding, this function could > also get moved to the main dw_mci driver. > >> +static int dw_mci_k3_suspend(struct device *dev) >> +{ >> + struct dw_mci *host = dev_get_drvdata(dev); >> + int ret = 0; >> + >> + ret = dw_mci_suspend(host); > > You should never initialize local variables when they are set later in the > function (the ret = 0 part above). For more complex functions, this prevents > gcc from warning you about accidentally uninitialized uses. > >> + if (!ret) >> + clk_disable_unprepare(host->ciu_clk); >> + >> + return ret; >> +} > > The suspend/resume code also looks very generic. Can't we make these the > default for dw-mci? If you do both, you won't even need a k3 specific driver. > I think in general we should try hard to add code like this to the common > driver when there is a chance that it can be shared with other platforms. Dw-mmc has the LOW_POWER mode feature at CLKENA register, this feature is running like clock-gating. So i have known it didn't control clock enable/disable in dw-mmc.c. Best Regards, Jaehoon Chung > > Arnd >