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Date: Thu, 31 Mar 2022 11:42:14 -0700
From: Bjorn Andersson <bjorn.andersson@...aro.org>
To: Shaik Sajida Bhanu <quic_c_sbhanu@...cinc.com>
Cc: adrian.hunter@...el.com, ulf.hansson@...aro.org,
robh+dt@...nel.org, quic_asutoshd@...cinc.com,
quic_rampraka@...cinc.com, quic_pragalla@...cinc.com,
quic_sartgarg@...cinc.com, quic_nitirawa@...cinc.com,
quic_sayalil@...cinc.com, agross@...nel.org,
krzysztof.kozlowski@...onical.com, linux-arm-msm@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] mmc: sdhci-msm: Reset GCC_SDCC_BCR register for SDHC
On Thu 31 Mar 00:03 PDT 2022, Shaik Sajida Bhanu wrote:
> Reset GCC_SDCC_BCR register before every fresh initilazation. This will
> reset whole SDHC-msm controller, clears the previous power control
> states and avoids, software reset timeout issues as below.
>
> [ 5.458061][ T262] mmc1: Reset 0x1 never completed.
> [ 5.462454][ T262] mmc1: sdhci: ============ SDHCI REGISTER DUMP ===========
> [ 5.469065][ T262] mmc1: sdhci: Sys addr: 0x00000000 | Version: 0x00007202
> [ 5.475688][ T262] mmc1: sdhci: Blk size: 0x00000000 | Blk cnt: 0x00000000
> [ 5.482315][ T262] mmc1: sdhci: Argument: 0x00000000 | Trn mode: 0x00000000
> [ 5.488927][ T262] mmc1: sdhci: Present: 0x01f800f0 | Host ctl: 0x00000000
> [ 5.495539][ T262] mmc1: sdhci: Power: 0x00000000 | Blk gap: 0x00000000
> [ 5.502162][ T262] mmc1: sdhci: Wake-up: 0x00000000 | Clock: 0x00000003
> [ 5.508768][ T262] mmc1: sdhci: Timeout: 0x00000000 | Int stat: 0x00000000
> [ 5.515381][ T262] mmc1: sdhci: Int enab: 0x00000000 | Sig enab: 0x00000000
> [ 5.521996][ T262] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000
> [ 5.528607][ T262] mmc1: sdhci: Caps: 0x362dc8b2 | Caps_1: 0x0000808f
> [ 5.535227][ T262] mmc1: sdhci: Cmd: 0x00000000 | Max curr: 0x00000000
> [ 5.541841][ T262] mmc1: sdhci: Resp[0]: 0x00000000 | Resp[1]: 0x00000000
> [ 5.548454][ T262] mmc1: sdhci: Resp[2]: 0x00000000 | Resp[3]: 0x00000000
> [ 5.555079][ T262] mmc1: sdhci: Host ctl2: 0x00000000
> [ 5.559651][ T262] mmc1: sdhci_msm: ----------- VENDOR REGISTER DUMP-----------
> [ 5.566621][ T262] mmc1: sdhci_msm: DLL sts: 0x00000000 | DLL cfg: 0x6000642c | DLL cfg2: 0x0020a000
> [ 5.575465][ T262] mmc1: sdhci_msm: DLL cfg3: 0x00000000 | DLL usr ctl: 0x00010800 | DDR cfg: 0x80040873
> [ 5.584658][ T262] mmc1: sdhci_msm: Vndr func: 0x00018a9c | Vndr func2 : 0xf88218a8 Vndr func3: 0x02626040
>
> Fixes: 0eb0d9f4de34 ("mmc: sdhci-msm: Initial support for Qualcomm chipsets")
> Signed-off-by: Shaik Sajida Bhanu <quic_c_sbhanu@...cinc.com>
> ---
>
> Changes since V2:
> - Dropped new line after fixes tag as suggested by Bjorn
> Andersson.
> - Passed device structure instead of passing platform_device
> structure as a argument for sdhci_msm_gcc_reset() as suggested
> by Bjorn Andersson.
> - Replaced dev_err() with dev_err_probe() as suggested by Bjorn
> Andersson.
Thanks, looks much better. Still some things I would like to see
improved below.
> Changes since V1:
> - Added fixes tag as suggested by Ulf Hansson.
> - Replaced devm_reset_control_get() with
> devm_reset_control_get_optional_exclusive() as suggested by
> Ulf Hansson.
> ---
> drivers/mmc/host/sdhci-msm.c | 39 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 39 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 50c71e0..e15e789 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -17,6 +17,7 @@
> #include <linux/regulator/consumer.h>
> #include <linux/interconnect.h>
> #include <linux/pinctrl/consumer.h>
> +#include <linux/reset.h>
>
> #include "sdhci-pltfm.h"
> #include "cqhci.h"
> @@ -284,6 +285,7 @@ struct sdhci_msm_host {
> bool uses_tassadar_dll;
> u32 dll_config;
> u32 ddr_config;
> + struct reset_control *core_reset;
> bool vqmmc_enabled;
> };
>
> @@ -2482,6 +2484,39 @@ static inline void sdhci_msm_get_of_property(struct platform_device *pdev,
> of_property_read_u32(node, "qcom,dll-config", &msm_host->dll_config);
> }
>
> +static int sdhci_msm_gcc_reset(struct device *dev, struct sdhci_host *host)
> +{
> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> + int ret = 0;
First use of this variable is an assignment, so no need to initialize it
here.
> +
> + msm_host->core_reset = devm_reset_control_get_optional_exclusive(dev, "core_reset");
reset-names will only be used to identify resets and hence there's no
reason to include "_reset" in the identifier.
If this is the only reset for the controller, there's actually no reason
for identifying it, you can omit reset-names from the binding and just
pass NULL here (to get the first resets = <>).
> + if (IS_ERR(msm_host->core_reset))
> + return dev_err_probe(dev, PTR_ERR(msm_host->core_reset),
> + "unable to acquire core_reset\n");
> +
> + if (!msm_host->core_reset)
> + return 0;
> +
> + ret = reset_control_assert(msm_host->core_reset);
> + if (ret)
> + return dev_err_probe(dev, ret, "core_reset assert failed\n");
> +
> + /*
> + * The hardware requirement for delay between assert/deassert
> + * is at least 3-4 sleep clock (32.7KHz) cycles, which comes to
> + * ~125us (4/32768). To be on the safe side add 200us delay.
> + */
> + usleep_range(200, 210);
> +
> + ret = reset_control_deassert(msm_host->core_reset);
> + if (ret)
> + return dev_err_probe(dev, ret, "core_reset deassert failed\n");
> +
> + usleep_range(200, 210);
> +
sdhci_msm_gcc_reset() is only called once during probe(), so there's no
reason to carry the reset_control pointer in struct sdhci_msm_host. Make
it a local variable and use reset_control_get_optional_exclusive() and
reset_control_put() the reset here before returning.
Regards,
Bjorn
> + return 0;
> +}
>
> static int sdhci_msm_probe(struct platform_device *pdev)
> {
> @@ -2529,6 +2564,10 @@ static int sdhci_msm_probe(struct platform_device *pdev)
>
> msm_host->saved_tuning_phase = INVALID_TUNING_PHASE;
>
> + ret = sdhci_msm_gcc_reset(&pdev->dev, host);
> + if (ret)
> + goto pltfm_free;
> +
> /* Setup SDCC bus voter clock. */
> msm_host->bus_clk = devm_clk_get(&pdev->dev, "bus");
> if (!IS_ERR(msm_host->bus_clk)) {
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>
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