[PATCH 6/7] OMAP: Serial: Allow UART parameters to be configured from board file
Sricharan R
r.sricharan at ti.com
Thu Mar 3 00:08:12 EST 2011
Hi,
>-----Original Message-----
>From: Govindraj [mailto:govindraj.ti at gmail.com]
>Sent: Wednesday, March 02, 2011 3:37 PM
>To: Sricharan R
>Cc: Govindraj.R; linux-omap at vger.kernel.org;
linux-serial at vger.kernel.org;
>linux-arm-kernel at lists.infradead.org; Jon Hunter; Tony Lindgren; Benoit
>Cousson; Kevin Hilman; Paul Walmsley; Rajendra Nayak; Deepak Kattungal
>Subject: Re: [PATCH 6/7] OMAP: Serial: Allow UART parameters to be
>configured from board file
>
>On Wed, Mar 2, 2011 at 1:49 PM, Sricharan R <r.sricharan at ti.com> wrote:
>> Hi,
>>>-----Original Message-----
>>>From: Govindraj [mailto:govindraj.ti at gmail.com]
>>>Sent: Wednesday, March 02, 2011 1:11 PM
>>>To: Sricharan R
>>>Cc: Govindraj.R; linux-omap at vger.kernel.org;
>> linux-serial at vger.kernel.org;
>>>linux-arm-kernel at lists.infradead.org; Jon Hunter; Tony Lindgren; Benoit
>>>Cousson; Kevin Hilman; Paul Walmsley; Rajendra Nayak; Deepak Kattungal
>>>Subject: Re: [PATCH 6/7] OMAP: Serial: Allow UART parameters to be
>>>configured from board file
>>>
>>>On Wed, Mar 2, 2011 at 12:46 AM, Sricharan R <r.sricharan at ti.com>
wrote:
>>>> Hi,
>>>>>diff --git a/arch/arm/mach-omap2/serial.c
>> b/arch/arm/mach-omap2/serial.c
>>>>>index 755f4aa..530e9e3 100644
>>>>>--- a/arch/arm/mach-omap2/serial.c
>>>>>+++ b/arch/arm/mach-omap2/serial.c
>>>>>@@ -44,6 +44,15 @@
>>>>>
>>>>> static int omap_uart_con_id __initdata = -1;
>>>>>
>>>>>+static struct omap_uart_port_info omap_serial_default_info[] = {
>>>>>+ {
>>>>>+ .dma_enabled = 0,
>>>>>+ .dma_rx_buf_size = DEFAULT_RXDMA_BUFSIZE,
>>>>>+ .dma_rx_timeout = DEFAULT_RXDMA_TIMEOUT,
>>>>>+ .idle_timeout = DEFAULT_IDLE_TIMEOUT,
>>>>>+ },
>>>>>+};
>>>>>+
>>>>> static int uart_idle_hwmod(struct omap_device *od)
>>>>> {
>>>>> omap_hwmod_idle(od->hwmods[0]);
>>>>>@@ -66,6 +75,54 @@ static struct omap_device_pm_latency
>>>> omap_uart_latency[]
>>>>>= {
>>>>> },
>>>>> };
>>>>>
>>>>>+#ifdef CONFIG_OMAP_MUX
>>>>>+static struct omap_device_pad default_serial0_pads[] __initdata = {
>>>>>+ {
>>>>>+ .name = "uart1_rx.uart1_rx",
>>>>>+ .flags = OMAP_DEVICE_PAD_REMUX |
>> OMAP_DEVICE_PAD_WAKEUP,
>>>>>+ .enable = OMAP_MUX_MODE0,
>>>>>+ },
>>>>>+};
>>>>>+
>>>>>+static struct omap_device_pad default_serial1_pads[] __initdata = {
>>>>>+ {
>>>>>+ .name = "uart2_rx.uart2_rx",
>>>>>+ .flags = OMAP_DEVICE_PAD_REMUX |
>> OMAP_DEVICE_PAD_WAKEUP,
>>>>>+ .enable = OMAP_MUX_MODE0,
>>>>>+ },
>>>>>+};
>>>>>+
>>>>>+static struct omap_device_pad default_serial2_pads[] __initdata = {
>>>>>+ {
>>>>>+ .name = "uart3_rx_irrx.uart3_rx_irrx",
>>>>>+ .flags = OMAP_DEVICE_PAD_REMUX |
>> OMAP_DEVICE_PAD_WAKEUP,
>>>>>+ .enable = OMAP_MUX_MODE0,
>>>>>+ },
>>>>>+};
>>>>>+
>>>>>+static struct omap_device_pad default_omap36xx_serial3_pads[]
>> __initdata
>>>> =
>>>>>{
>>>>>+ {
>>>>>+ .name = "gpmc_wait3.uart4_rx",
>>>>>+ .flags = OMAP_DEVICE_PAD_REMUX |
>> OMAP_DEVICE_PAD_WAKEUP,
>>>>>+ .enable = OMAP_MUX_MODE2,
>>>>>+ },
>>>>>+};
>>>>>+
>>>>>+static struct omap_device_pad default_omap4_serial3_pads[]
__initdata
>> =
>>>> {
>>>>>+ {
>>>>>+ .name = "uart4_rx.uart4_rx",
>>>>>+ .flags = OMAP_DEVICE_PAD_REMUX |
>> OMAP_DEVICE_PAD_WAKEUP,
>>>>>+ .enable = OMAP_MUX_MODE0,
>>>>>+ },
>>>>>+};
>>>> Here only the UART RX pins are muxed, so what about the cts, rts, tx
>>>pins?
>>>
>>>The intention here is to enable wakeup capabilities for uart rx pad.
>>>
>>>AFAIK most of the boards are currently dependent on bootloader for
>>>uart-muxing if any board is not dependent on bootloader then we
>>>can use omap_serial_init_port along with board_mux_info from board.
>>>
>> Yes. The idea is to be independent of the bootloaders for mux settings.
>>
>>>Prior to this change uart wakeup is based on rx_pad and we were
>> populating
>>>offset and using omap_ctrl api's to read/write which is cleaned up now.
>>>Most of boards are dependent on uart-rx wakeup to avoid breaking any
>>>board support we
>>>are using omap_serial_init by filling default values, which provides
>>>us with same
>>>environment but with right approach towards handling mux data with a
>>>handshake with
>>>hwmod framework.
>>>
>> Now, in this change only the RX pin is configured. So if some board
uses
>> omap_serial_init then only the RX is going to be configured.
>> How will they configure the rest of the pins?
>
>
>They should call omap_serial_init_port to configure each individual uart
>with
>mux_info filled and not use omap_serial_init.
>
>If any board is not dependent for mux from u-boot then they use above
said
>init_port func.
>
>
>> They cannot call omap_serial_init_port after this just to configure the
>> rest of the mux pins( cts, rts, tx).
>
>No. You need to use either omap_serial_init_port or omap_serial_init
>you cannot call both apis from board file please refer to both func
>documentation.
>
>Also please note i am not configuring all uart pins for pullups and pull
>downs
>with this patch series and its not related to this patch series.
>I am only enabling wakeup-enable pin for rx as it was done before.
>
>> So data which is passed from omap_serial_init should have the
>> configuration
>> for all the pins, and this default data should be consistent across
>> atleast
>> some boards, so that they can use this. This will reduce the data
>> duplication across board files.
>>
>> If this is not true, then all the pads can be configured from the board
>> files itself using omap_serial_init_port and you can set the required
>> RX wakeup capability there as well.
>>
>
>Yes that be done but currently but that is not in my intention here
>with my patch
>I just want to retain rx wakeup by default to avoid breaking support
>for any board.
>
>Adding pin mux for each individual pin is a separate activity where I
also
>need access to various boards So I am leaving that to developers who
>want to configure
>for the corresponding boards using init_port api.
>
>Removing mux from u-boot level and adding it to board file is beyond
>the scope of this
>patch series and is a separate topic of discussion, as current patch
series
>assumes that uarts are muxed from u-boot level and needs to only enable
>wakeup
>capability for rx-pin.
>
>Hope this clarifies.
>
It is true that this patch is not intending to configure the pads.
But my question is, after this patch say
1) some board file calls omap_serial_port.
2) As a result , all the uarts devices are build and only the Rx pad is
configured for each device.
3) After this there will be no way of configuring the rest of the pads
??
That should not happen. Also relying that the bootloaders are going
to do the configuration is not correct.
So if some board calls omap_serial_port then there should be default
values for all pads which a board can use, otherwise the board calls
omap_serial_init_port for each of the device.
>--
>Thanks,
>Govindraj.R
>
>
>>>So if any board needs specific mux they can go ahead and add required
>>>mux data in
>>>board file and use map_serial_init_port instead of current
>>>omap_serial_init.
>>>
>>>
>>>> Is it consistent that across all socs that only UART3 would have
>>>UART/IRDA
>>>> functions capability so that serial2 pads can always be called
>> "rx_irxx"
>>>> ?.
>>>
>>>Yes from OMAP2420 to OMAP4430 uart3 can used as irda.
>>>
>> Ok.
>>>--
>>>Thanks,
>>>Govindraj.R
>>
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